You mean DBZ: Supersonic Warriors 2?
Well, it is pretty fun, for a while, but the gameplay isn't as smooth as the 1st game. Sure, you've got more characters, more moves, better graphics and such, but you are pretty limited to what you can do with Melee. In the first Supersonic Warriors game, you could teleport right next to your opponent, and even deterimine at what angle, but you can't do that in SW 2.
Also, in SW 1, you could use a Dash to get around the arena faster, and as soon as you stopped dashing, you would slowly come to a halt again in a smooth way. In SW 2, you instantly stop. It feels unnatural and it really hinders melee, because you can't dash to your opponent, then use your momentum to glide further.
There's lots of little things like that. I'm a master at SW 1, but I still prefer playing it over SW 2.
SW 2 is fun for a while, but SW 1 has greater depth in its combat system, IMO.
As for other DS titles worth getting:
- Phoenix Wright: Ace Attorney
- Sonic Rush
- Megaman ZX
Those are must-have titles, in my opinion. o/
There are plenty more, I'm sure, but those are the ones I could think of right now.