Okami is my 3rd favorite game of all time, so I was excited to play it's only sequel, but while it's definitely not a bad game, it just doesn't really live up to it's predecessor.
I think they should have waited until the 3ds to make this game, I do think the ds is a perfect fit for okami with the touch screen, but this game is a bit too ambitious for what the hardware allows. The controls can be a bit sluggish, which becomes much worse when the game tries to do more intense things for boss battles, and the game straight up can run slowly sometimes, this is most noticeable in sei'an city.
Now, it's not a bad game, a lot of what made okami so good to begin with is still here. It's gorgeous artstyle, fun exploration, and enjoyable zelda-like adventuring is still here, just in a different form due to the hardware.
If you are looking for zelda-likes on the ds, or are just a fan of okami, it's worth a shot, but don't expect it to be as good.