Easily the best in the Dark Matter trilogy. The pastel/anime style makes the visuals look gorgeous on the N64 and there's nothing quite like it in the console's library.
In regards to the gameplay, Kirby can feel a little too slow at times but it's easy to get used to. However, the best part is the inclusion of fusing copy abilities. Even if not all of them are easy to use, it makes the game feel fresh from start to finish. Besides, the level design is pretty fun and the level themes are extremely creative making the experience all the more memorable.
Overall, one of the best Kirby games I've played and a very fun platformer in general.