As the only official way to play the Rush Duel format for players outside of Japan this game is somewhat of a requirement for anyone with any interest in experiencing it.
My opinion on Rush Duels themselves is that they are OK. They're not as good as my favourite era of Yu-Gi-Oh, which is kind of late GX era, but they're much better than the clusterfuck that Yu-Gi-Oh is today. While combos aren't completely removed, there's far less focus on letting players spend 10 minute turns activating effect after effect, since spells and traps are simplified massively (no chains even exist) and every monster effect is once per turn. Being able to mass summon every monster in your hand per turn is interesting, as it means lower level monsters have a somewhat less important role since they tend to get sacrificed instantly, but you still need more than enough to not brick into a hand of tribute-only monsters.
Drawing up to a brand new hand of 5 every turn allowed duels to become very swingy. Every single turn you and your opponent get a brand new hand with no penalty for using all your cards, and no restrictions on summoning per turn, it is very hard to build up an unbeatable board. Sometimes you'll even use a monsters effect which has a cost to discard a card from your hand even when you don't need to just so you can draw an extra card next turn.
This format did have some very notable flaws though. Since you can summon as many monsters as you want, I found it was way too easy to just set 3 defense monsters every turn, meaning even if they have a full board of unbeatable monsters, unless they have piercing or position changing effects, you can wall them completely (this will lead to you decking out faster though so it's not a perfect plan, but it's great for stalling a few turns).
The maximum monsters are a neat concept exclusive to this format. Combine 3 specific cards Exodia-style, but instead of instantly winning, they form on the field together to create one super-monster, with the effects of all 3. It is only allowed to attack once per turn though, so it's even easier to stall against without the right cards to let you pierce or change opponents monsters to attack position. Also I think there's only 3 of them in the entire game, 2 of which are post-game exclusive.
One of the most disappointing things about the game is the lack of card variety. There's just over 350 in the whole game, many of which are locked behind post-game packs (2 of 6 total packs). That's less than the games that were coming out on GBA... I know it was a new format at the time, but why not just wait for more releases if you barely have enough to fill a game?
I will say though this game does utilise its cards much better than early main game Yu-Gi-Oh. While the real game focused heavily on generic beatdown with flexible staple cards, the cards in this game all seem focused on running a specific type of monster. Sometimes you'll get even more specific card themes, like 0 atk monsters, or normal monsters. You get very few spell and traps that can be thrown in to any deck, as most of them have requirements to only fit a specific focus of cards.
Having said that, I found the original starter deck to be so strong that I never really switched it at all. It's a spellcaster deck and contains 3 copies of a mirror force-esque card specific to spellcasters. As far as I remember, almost no other types had a card like this, making it way too good to pass up for another type of deck. Also there's no main phase 2 in this game, so if your opponents board is wiped out by the trap they'll be completely defenceless on your turn, outside of any traps they set themselves (and as mentioned most, if any, decks outside of spellcasters do not have any traps that can wipe a board).
The game does have a weird thing where until the post-game you can't actually edit your own deck. You can only use deck recipes which are taken when winning duels or bought from the shop. Not that it mattered to me since, like I said, the starter deck was so powerful I never really felt the need to grind out cards for other decks anyway.
Also that's technically a lie, you can unlock deck editing early by standing in a very specific spot and entering the Konami code. You'd never think to do this unless you looked it up online though. I actually did do it, but I still only ever used the feature to make tiny changes to the starting spellcaster deck along the way lol. Getting enough cards to even make a good deck for other types is tough with the limited card pool, even ignoring the fact the first deck gives you triple of one of the best traps in the game that only works in that deck.
One other thing that makes deck building a pain in the ass is the lack of a search bar. You can filter a lot of stuff which works for monsters, but trying to wade through all the spells and traps for the ones that work for specific types is just annoying. Just let me search cards that mention "Dragon" or "Machine", c'mon. Or hell, let me filter spell/traps and type at the same time to only get spells and traps that work with specific types.
As far as the game outside the Rush Duels themselves go, I don't like it. The performance when walking around the world was choppy as hell, and the characters, based on the anime which I haven't seen, are all extremely annoying and one dimensional.
The presentation in duels is fine, but he cards don't get full 3D models on the field like the DS games, they just have their artwork blown up as a static png. If the card artwork only shows the upperbody, that's all it will show on the screen. Kind of lazy, but better than most modern Yu-Gi-Oh games which don't show any kind of monster coming out of the cards when on the field.
At least all 2-tribute monsters (and some 1 tribute ones) get a full animated cutscene when being summoned, which luckily can be turned off if you want.
Also while I don't let the prices of games affect my ratings for them, there's no way this game is worth the asking price. Get it on sale if you're going to get it at all.
My opinion on Rush Duels themselves is that they are OK. They're not as good as my favourite era of Yu-Gi-Oh, which is kind of late GX era, but they're much better than the clusterfuck that Yu-Gi-Oh is today. While combos aren't completely removed, there's far less focus on letting players spend 10 minute turns activating effect after effect, since spells and traps are simplified massively (no chains even exist) and every monster effect is once per turn. Being able to mass summon every monster in your hand per turn is interesting, as it means lower level monsters have a somewhat less important role since they tend to get sacrificed instantly, but you still need more than enough to not brick into a hand of tribute-only monsters.
Drawing up to a brand new hand of 5 every turn allowed duels to become very swingy. Every single turn you and your opponent get a brand new hand with no penalty for using all your cards, and no restrictions on summoning per turn, it is very hard to build up an unbeatable board. Sometimes you'll even use a monsters effect which has a cost to discard a card from your hand even when you don't need to just so you can draw an extra card next turn.
This format did have some very notable flaws though. Since you can summon as many monsters as you want, I found it was way too easy to just set 3 defense monsters every turn, meaning even if they have a full board of unbeatable monsters, unless they have piercing or position changing effects, you can wall them completely (this will lead to you decking out faster though so it's not a perfect plan, but it's great for stalling a few turns).
The maximum monsters are a neat concept exclusive to this format. Combine 3 specific cards Exodia-style, but instead of instantly winning, they form on the field together to create one super-monster, with the effects of all 3. It is only allowed to attack once per turn though, so it's even easier to stall against without the right cards to let you pierce or change opponents monsters to attack position. Also I think there's only 3 of them in the entire game, 2 of which are post-game exclusive.
One of the most disappointing things about the game is the lack of card variety. There's just over 350 in the whole game, many of which are locked behind post-game packs (2 of 6 total packs). That's less than the games that were coming out on GBA... I know it was a new format at the time, but why not just wait for more releases if you barely have enough to fill a game?
I will say though this game does utilise its cards much better than early main game Yu-Gi-Oh. While the real game focused heavily on generic beatdown with flexible staple cards, the cards in this game all seem focused on running a specific type of monster. Sometimes you'll get even more specific card themes, like 0 atk monsters, or normal monsters. You get very few spell and traps that can be thrown in to any deck, as most of them have requirements to only fit a specific focus of cards.
Having said that, I found the original starter deck to be so strong that I never really switched it at all. It's a spellcaster deck and contains 3 copies of a mirror force-esque card specific to spellcasters. As far as I remember, almost no other types had a card like this, making it way too good to pass up for another type of deck. Also there's no main phase 2 in this game, so if your opponents board is wiped out by the trap they'll be completely defenceless on your turn, outside of any traps they set themselves (and as mentioned most, if any, decks outside of spellcasters do not have any traps that can wipe a board).
The game does have a weird thing where until the post-game you can't actually edit your own deck. You can only use deck recipes which are taken when winning duels or bought from the shop. Not that it mattered to me since, like I said, the starter deck was so powerful I never really felt the need to grind out cards for other decks anyway.
Also that's technically a lie, you can unlock deck editing early by standing in a very specific spot and entering the Konami code. You'd never think to do this unless you looked it up online though. I actually did do it, but I still only ever used the feature to make tiny changes to the starting spellcaster deck along the way lol. Getting enough cards to even make a good deck for other types is tough with the limited card pool, even ignoring the fact the first deck gives you triple of one of the best traps in the game that only works in that deck.
One other thing that makes deck building a pain in the ass is the lack of a search bar. You can filter a lot of stuff which works for monsters, but trying to wade through all the spells and traps for the ones that work for specific types is just annoying. Just let me search cards that mention "Dragon" or "Machine", c'mon. Or hell, let me filter spell/traps and type at the same time to only get spells and traps that work with specific types.
As far as the game outside the Rush Duels themselves go, I don't like it. The performance when walking around the world was choppy as hell, and the characters, based on the anime which I haven't seen, are all extremely annoying and one dimensional.
The presentation in duels is fine, but he cards don't get full 3D models on the field like the DS games, they just have their artwork blown up as a static png. If the card artwork only shows the upperbody, that's all it will show on the screen. Kind of lazy, but better than most modern Yu-Gi-Oh games which don't show any kind of monster coming out of the cards when on the field.
At least all 2-tribute monsters (and some 1 tribute ones) get a full animated cutscene when being summoned, which luckily can be turned off if you want.
Also while I don't let the prices of games affect my ratings for them, there's no way this game is worth the asking price. Get it on sale if you're going to get it at all.