Unfortunately, I have to be the dissenting opinion here. Guardian Signs takes some interesting steps forward, but a lot of steps backward from my experience.
There are a lot of little things that, in my opinion, waste a lot of time over a run of the game. The biggest culprit is that backtracking sucks, and that the Pokemon ride mechanic and the need to summon via Guardian Signs are closely related to that. While I think the concept is super cool (and does eventually save time when you get Latias/Latios), there are quite a few problems here:
1. An animation plays every time you tap the Guardian Sign button, and another animation plays every time the Pokemon is successfully summoned.
2. Talking to NPCs that start/end quests will automatically dismount you from your Ride Pokemon.
3. You can't enter certain areas with Ride Pokemon. Which seems obvious and shouldn't be a problem, but this doesn't just apply to doorways; this also applies to cave entrances and narrow passageways.
4. There are quite a few sections that are either timing based movement sections (the avalanche section for example, or the lightning in a lake section), where you obviously cannot move with Ride Pokemon and have to dismount.
5. You can't summon other Ride Pokemon while riding a Pokemon. So, you have to dismount the Ride Pokemon (which also has an animation) and then summon the next Ride Pokemon with the Guardian Sign. This is essential because...
6. Certain sections require you to use multiple Ride Pokemon to traverse and thus you will have to swap between them. In addition, most of Oblivia cannot be traversed on foot and will at some point, require the Staraptor/Lati@s.
7. You can't fly from everywhere in Oblivia (even though there are parts where I think you should be able to); some sections like up on the Radio Tower and the snowy mountain will not let you fly off, and you will have to walk back to the base to do so.
As a result, I think 20% of the game was spent with Ride Pokemon summoning/dismounting animations, and it really starts to wear you down.
There's a lot of other little timewasters in the game too. Often between missions, you'll be asked to just go back and forth between places to talk to NPCs to progress the plot with mostly filler dialogue. A lot of the side quests are also more or less fetch quests (deliver this item to a far away location, get me this Pokemon from far away, etc), and if you need specific Pokemon with stronger field abilities that are required for clearing obstacles and catching hidden Pokemon, that's a fetch quest in itself. There are a couple of forced stealth sections where getting caught is an automatic teleport back to the start, and do feel quite out of place. And then of course, you've got agitated Pokemon as a mechanic.
Agitated Pokemon as a mechanic is probably the 2nd most egregious time waster in this game, but in some ways, even more aggravating than the Ranger Sign animations I talked about above. The way the mechanic works is, aggravated Pokemon will attack more often (as expected), and take significantly less damage from the player's stylus until the entire red bar is depleted; think of it as a 2nd wind/health bar mechanic that's either present at the start (for wild encounters/some enemy team attacks). That slows down the combat a fair bit, and you have to rely heavily on your partner Pichu to wear it down (which is RNG when it shows up by the way; sometimes it will show up immediately and sometimes it takes a good minute) or place other helper Pokemon down, which can be pretty risky because if they get chipped by any attack regardless of matchup, they're gone forever and you'll probably have to go back and get them. Practically every boss fight utilizes this mechanic too to double the length of the fight, and it feels somewhat cheap. Oh, and if a wild Pokemon is agitated, you can't run away from them until the red bar is gone. And some wild Pokemon as their agitation behavior will run at you, so you have to catch those specific species, otherwise after disengaging from combat, they will remain agitated in the overworld and reenter combat again with you with a fresh new red bar, because you don't get many invincibility frames from running away and agitation doesn't go away unless they're outright removed from the overworld by catching.
I'm also not pleased that a good chunk of content is locked behind the need for multiplayer. Again, I think the concept is super cool if you've got friends with the game (though it is admittingly a bit repetitive). The main issue is that there's a lot of side story (and important side story to the history leading to the main plot, I'd say) locked behind the multiplayer missions, and some Pokemon cannot be discovered/caught without completing certain multiplayer missions. You can technically complete all the missions solo, but they become extremely difficult because the multiplayer missions have a separate leveling up system than the main game and don't give out much experience. So, you have to grind (a lot) to get to the end of the multiplayer experience solo, because it does not scale for the number of players, something that I wish it did.
At the end of the day, it's still a Pokemon Ranger game, so it's still fun. Sure, the villains are very shallow and the side cast is somewhat bland, and the plot is not quite as rich as Shadows of Almia (in my opinion), but it's still a ton of fun rapidly spamming circles around wild Pokemon, and the colorful pixel visuals and pleasant soundtrack help a lot as well. But there's a lot of little things that mar the overall experience here and there, and it quite annoys me because I think it's got great potential, but somewhat botches the execution due to sloppy decisions made throughout the game. It's probably still worth a shot if you liked the original game and Shadows of Almia, but I won't deny that I have many reservations recommending this game and that it left me a little disappointed. I definitely can't recommend trying to 100% this game unless you have a friend that is just as determined as you are to grind with you through the multiplayer.
There are a lot of little things that, in my opinion, waste a lot of time over a run of the game. The biggest culprit is that backtracking sucks, and that the Pokemon ride mechanic and the need to summon via Guardian Signs are closely related to that. While I think the concept is super cool (and does eventually save time when you get Latias/Latios), there are quite a few problems here:
1. An animation plays every time you tap the Guardian Sign button, and another animation plays every time the Pokemon is successfully summoned.
2. Talking to NPCs that start/end quests will automatically dismount you from your Ride Pokemon.
3. You can't enter certain areas with Ride Pokemon. Which seems obvious and shouldn't be a problem, but this doesn't just apply to doorways; this also applies to cave entrances and narrow passageways.
4. There are quite a few sections that are either timing based movement sections (the avalanche section for example, or the lightning in a lake section), where you obviously cannot move with Ride Pokemon and have to dismount.
5. You can't summon other Ride Pokemon while riding a Pokemon. So, you have to dismount the Ride Pokemon (which also has an animation) and then summon the next Ride Pokemon with the Guardian Sign. This is essential because...
6. Certain sections require you to use multiple Ride Pokemon to traverse and thus you will have to swap between them. In addition, most of Oblivia cannot be traversed on foot and will at some point, require the Staraptor/Lati@s.
7. You can't fly from everywhere in Oblivia (even though there are parts where I think you should be able to); some sections like up on the Radio Tower and the snowy mountain will not let you fly off, and you will have to walk back to the base to do so.
As a result, I think 20% of the game was spent with Ride Pokemon summoning/dismounting animations, and it really starts to wear you down.
There's a lot of other little timewasters in the game too. Often between missions, you'll be asked to just go back and forth between places to talk to NPCs to progress the plot with mostly filler dialogue. A lot of the side quests are also more or less fetch quests (deliver this item to a far away location, get me this Pokemon from far away, etc), and if you need specific Pokemon with stronger field abilities that are required for clearing obstacles and catching hidden Pokemon, that's a fetch quest in itself. There are a couple of forced stealth sections where getting caught is an automatic teleport back to the start, and do feel quite out of place. And then of course, you've got agitated Pokemon as a mechanic.
Agitated Pokemon as a mechanic is probably the 2nd most egregious time waster in this game, but in some ways, even more aggravating than the Ranger Sign animations I talked about above. The way the mechanic works is, aggravated Pokemon will attack more often (as expected), and take significantly less damage from the player's stylus until the entire red bar is depleted; think of it as a 2nd wind/health bar mechanic that's either present at the start (for wild encounters/some enemy team attacks). That slows down the combat a fair bit, and you have to rely heavily on your partner Pichu to wear it down (which is RNG when it shows up by the way; sometimes it will show up immediately and sometimes it takes a good minute) or place other helper Pokemon down, which can be pretty risky because if they get chipped by any attack regardless of matchup, they're gone forever and you'll probably have to go back and get them. Practically every boss fight utilizes this mechanic too to double the length of the fight, and it feels somewhat cheap. Oh, and if a wild Pokemon is agitated, you can't run away from them until the red bar is gone. And some wild Pokemon as their agitation behavior will run at you, so you have to catch those specific species, otherwise after disengaging from combat, they will remain agitated in the overworld and reenter combat again with you with a fresh new red bar, because you don't get many invincibility frames from running away and agitation doesn't go away unless they're outright removed from the overworld by catching.
I'm also not pleased that a good chunk of content is locked behind the need for multiplayer. Again, I think the concept is super cool if you've got friends with the game (though it is admittingly a bit repetitive). The main issue is that there's a lot of side story (and important side story to the history leading to the main plot, I'd say) locked behind the multiplayer missions, and some Pokemon cannot be discovered/caught without completing certain multiplayer missions. You can technically complete all the missions solo, but they become extremely difficult because the multiplayer missions have a separate leveling up system than the main game and don't give out much experience. So, you have to grind (a lot) to get to the end of the multiplayer experience solo, because it does not scale for the number of players, something that I wish it did.
At the end of the day, it's still a Pokemon Ranger game, so it's still fun. Sure, the villains are very shallow and the side cast is somewhat bland, and the plot is not quite as rich as Shadows of Almia (in my opinion), but it's still a ton of fun rapidly spamming circles around wild Pokemon, and the colorful pixel visuals and pleasant soundtrack help a lot as well. But there's a lot of little things that mar the overall experience here and there, and it quite annoys me because I think it's got great potential, but somewhat botches the execution due to sloppy decisions made throughout the game. It's probably still worth a shot if you liked the original game and Shadows of Almia, but I won't deny that I have many reservations recommending this game and that it left me a little disappointed. I definitely can't recommend trying to 100% this game unless you have a friend that is just as determined as you are to grind with you through the multiplayer.