It's incredibly short, even for a Kirby game, with a story that's just bad. It has Dedede as the first boss. It has the Metal ability. Heck, having the metal ability alone would make a game suck. The maps were too straightforward, with quite a few "levels" that were only one room, which is stupid. The new enemies were awful; the majority of them were blobs with eyes smacked on them and we were expected to assume that was somehow not lazy. A lot of the copy scrolls were lazy as well (what the heck Beam/hi-jump). I could go on.
Honestly it is not an awful game. But it is really bad by Kirby standards.