It's pretty good, but damn is it hard and borderline unfair in places with its enemy placement and speed. Really didn't expect that from a Kirby game going in, and I've spent my childhood dying a lot in the harder parts of Kirby's Dream Land 2. Was Kirby's Adventure also this tough?
All in all I'd say I prefer Kirby & the Amazing Mirror, which runs on the same engine but has some more interesting abilities and feels like it controls a bit better.