An Extremely Well Done Game
I'm currently playing this game for the first time, and I'm already through the main portion of the game and into the "bonus" stages. I'm amazed with the craftiness of a lot of the levels - I'd say that 80 or 90 percent of the levels are a blast to play while only a minority are laborious or tedious. The game has a puzzle element to go with platforming, and it really does feel like a perfect mix of a traditional Mario game and a classic Donkey Kong title.
It's easy to pick up, play for 10 minutes, and put back down without feeling like you have to catch up the next time you play. The graphics are well done for a GBA game, and the music and voice acting is well done. My only complaint is that some levels can be frustrating (if you're trying to collect everything), but the good easily outweighs the bad.