Although the second game in many respects is better than Katamari Damacy, with a whole year of work, there could have been more to the game. The game was definately longer, and the new types of modes and multiplayer options make this game really fun, but it failed to innovate on the first game. I'll break it down by catagory to make it easy to understand.
Graphics - 8/10 - The first game had incredible cartoony and fun Japanese humor in 3D form. Crisper edges, and more vivid colors make this game's graphics pop a little more from the first game, but is mostly running on the same engine, which is somewhat disappointing, but expected. Even though it does use mostly the same engine, everything still looks really nice, and isn't an eyesoar to look at.
Gameplay - 10/10 - Just as fun as ever. Good framerate and some of the technical problems that were in the first game were solved, which is really nice. Although there were minor differences in gameplay for each cousin, it would have been nice to see a larger variation, but either way, it was pretty good. The new types of levels really came out nicely, and don't seem awkward like I thought they would, and glitches and bugs are realatively low.
Sound - 10/10 - Probably the best part of this game. Amazing soundtrack, hilarious noises, and great bass. Just as the first game, this brings this game to an all time excellence. I wish the entire game could be as good as the sound, but even though it isn't, it doesn't make it a bad game.
Replay Value - 8/10 - The new co-op mode is alright, but my friend is really bad at listening, so it wasn't too exciting. The battle mode is still fun, and I liked how they made variety in it this time. You can now multiplay to collect the most of a certain type of item instead of just making a larger Katamari. The game was a little longer than the first game, which is good, and expected due to the price of game increasing from $20 to $30 over the previous one.
BOTTOM LINE - If you liked or played the first game, get it... and if your looking for a light hearted, fun, and way out there game, We Love Katamari fits your mold.