This game is... outdated. I remember sitting in the library in 7th and 8th grade and playing the first two. They were fun. But I think that the audience of nostalgic players are too mature for this game to be good on a substantial level. Let me state some more objective things about the game first though.
The mechanics of this game are simple and rather flawless, with good tight controls. The music in each world is catchy and fun and lighthearted, fitting the game it is for. The art style is on par with the rest of the serious, not being either good or bad, but consistent and well done. The dialogue is fun and humorous for the young and the young-at-heart. The gameplay isn't too difficult, but poses enough challenge for all players, new and old alike. The boss is a challenge, but not too difficult where it would seem impossible and unfun.
Now more of an opinionated review. The controls were good, but sometimes felt a bit slow for me, though maybe it was just the physics of the game having a relatively low max speed. The music was pretty catchy, but when trying to collect everything in each level, it just droned on and on. The dialogue was painful to read through, being both far too childish and strangely paced, being that the thought bubbles required a command to get through as well as changing over time, and sometimes were skipped entirely if you weren't careful. The game itself was easy, but it felt too slow because trying to gather all the squiggles and stars took twice as much time as getting through just the story itself.
I hope this was constructive, destructive criticism isn't really useful, now, is it? I just felt, through the whole game, that the only reason I was playing it was that I had to because I finished the older ones. I played it only for a hope at nostalgic fun, which was rather poorly received. I'm sure, however, that a newer generation would enjoy this much more than I did. That isn't to say it was fun, it just wasn't for me.