It's like if you took the Super Robot Wars series, focused it entirely on Gundam series, included a massive selection of characters and mobile suits to pilot where anyone could pilot anything, and then made it worse in every other way.
The story of the game is retelling different series, films, and manga covering the Wing, Seed, 00, and Iron Blooded Orphan timelines for a total of 13 different series of missions. Three for Gundam, five for Seed, three for 00, and two for Iron Blooded Orphans. The problem with that is if you know the story you are getting a very dull retelling and if you don't know the story you are missing massive amounts of context and characterization (and sometimes entire characters). It also means that the battles you fight would be limited to units from the scenario, except that you can take a group attached to a warship (9 units and the base) and a raid unit (8 units) that you select the pilots and mechs for over the course of the entire game. The actual maps aren't done very well either, as many of the represented battles didn't actually even have many units in the plot, leading to maps just throwing random generic enemy units in all corners just to give you something to do.
This, of course, means that there is absolutely no balance to this game and you will easily destroy everything even when selecting the harder difficulty and even without making use of funds and obtained skills to make your pilots and mechs even stronger (upgrading pilots being the normal way to completely break SRW series games). Adding to the lack of balance is the raid attacks both groups are capable of that could easily take out 2-9 units just from one action. You can switch to pilots and mechs that are of lower level but then you are probably just using things that you don't want to use.
The actual combat just isn't as good as the SRW series with the much more limited focus on skills, lack of secrets, not having you switch your lineup, and with inferior combat animations. The strangest combat animations comes from the first shot or shots always visually missing before later shots hit even when certain attack should only have fired once, always looking terrible and not even making sense in some situations. The Wing Gundam missing the first twin beam rifle shot or a sniper unit missing a massive capital ship after their character says a line about taking one shot only to then fire two more shots that hit the target. A lot of units basically end up with similar weapons or moving in a similar way giving you little reason to want to bother with anything but the more unique and strongest units that are available.
The stories are rarely told well in even the combat scenarios with limited plot cutscenes or combat animations and character deaths often left out, sometimes being available only if you intentionally get them killed. Iron Blooded Orphans is even missing a major battle, antagonist, and important story moment for some reason. Though that series was often handled the best with some more unique scenarios and better story focus.
There is an almost mobile game style feature to gain money and items where you send one or two of your available built groups out to complete missions from a large list. After the assigned time (possibly a couple hours to close to a full day) the group will be available again with some extra XP and you will get your item rewards. Each of these missions has a short description but you don't even get any kind of information about how they completed the task. Each could easily have been made into a side mission (especially when the game doesn't care at all about balance which is the only real difficult part of making missions in a game like this) but instead they serve only to go along with the game's odd need to continue to obtain money in order to not only build mobile suits but to buy the pilots you have unlocked that you want to use.
If you are a big Gundam fan using all the characters and suits can be fun and it's nice to see scenarios for a lot of the side stories but it's just never very fun to play and does nothing interesting with the material.
The story of the game is retelling different series, films, and manga covering the Wing, Seed, 00, and Iron Blooded Orphan timelines for a total of 13 different series of missions. Three for Gundam, five for Seed, three for 00, and two for Iron Blooded Orphans. The problem with that is if you know the story you are getting a very dull retelling and if you don't know the story you are missing massive amounts of context and characterization (and sometimes entire characters). It also means that the battles you fight would be limited to units from the scenario, except that you can take a group attached to a warship (9 units and the base) and a raid unit (8 units) that you select the pilots and mechs for over the course of the entire game. The actual maps aren't done very well either, as many of the represented battles didn't actually even have many units in the plot, leading to maps just throwing random generic enemy units in all corners just to give you something to do.
This, of course, means that there is absolutely no balance to this game and you will easily destroy everything even when selecting the harder difficulty and even without making use of funds and obtained skills to make your pilots and mechs even stronger (upgrading pilots being the normal way to completely break SRW series games). Adding to the lack of balance is the raid attacks both groups are capable of that could easily take out 2-9 units just from one action. You can switch to pilots and mechs that are of lower level but then you are probably just using things that you don't want to use.
The actual combat just isn't as good as the SRW series with the much more limited focus on skills, lack of secrets, not having you switch your lineup, and with inferior combat animations. The strangest combat animations comes from the first shot or shots always visually missing before later shots hit even when certain attack should only have fired once, always looking terrible and not even making sense in some situations. The Wing Gundam missing the first twin beam rifle shot or a sniper unit missing a massive capital ship after their character says a line about taking one shot only to then fire two more shots that hit the target. A lot of units basically end up with similar weapons or moving in a similar way giving you little reason to want to bother with anything but the more unique and strongest units that are available.
The stories are rarely told well in even the combat scenarios with limited plot cutscenes or combat animations and character deaths often left out, sometimes being available only if you intentionally get them killed. Iron Blooded Orphans is even missing a major battle, antagonist, and important story moment for some reason. Though that series was often handled the best with some more unique scenarios and better story focus.
There is an almost mobile game style feature to gain money and items where you send one or two of your available built groups out to complete missions from a large list. After the assigned time (possibly a couple hours to close to a full day) the group will be available again with some extra XP and you will get your item rewards. Each of these missions has a short description but you don't even get any kind of information about how they completed the task. Each could easily have been made into a side mission (especially when the game doesn't care at all about balance which is the only real difficult part of making missions in a game like this) but instead they serve only to go along with the game's odd need to continue to obtain money in order to not only build mobile suits but to buy the pilots you have unlocked that you want to use.
If you are a big Gundam fan using all the characters and suits can be fun and it's nice to see scenarios for a lot of the side stories but it's just never very fun to play and does nothing interesting with the material.