Very solid hand-held platformer.
WarioLand 3 is excuse enough to own a Game Boy Color. This is how hand-held games should be. Quick gameplay, simple controls & a solid storyline that's immersive but not complicated. Let's face it, if we wanted a complex & involving plotline with twists & side-stories, we'd pick up a home console game. Hand-helds were designed to play video games on the go, which to me implies something fast-paced & simple, something you could do during recess at school or on break at work or even in the bathroom while dropping a duece (hey, your dad has the newspaper, you have video games).
WL3 accomplishes just that. Each level has a main goal, which is getting a key & unlocking the corresponding chest (4 keys/chests per level). Get a key, unlock a chest, bam! save & get back to work. Every chest unlocked opens up a either a new level or access to other parts of previous levels via a world event or gaining a special move.
Controls aren't hard to learn (duh), especially since there's tutorials available for Wario's "special moves" whenever you pause. And the majority of them aren't advanced at all, they simple make your existing abilities more powerful (can't make it too complex - it's a Game Boy!).
The world in which Wario fights his way through is actually quite diverse. There are four main areas, each with various stages that are vast in their own right. Slowly gaining access to various parts of each stage to complete the game is exciting in itself but Nintendo expanded on that. WL3 is non-linear - you aren't restricted to a strict path. You can bounce around from stage to stage for whatever reason as you see fit. And doing so increases your reward, since there's a difference between beating a game and COMPLETING a game.
Difficulty - well, it's not difficult persay, but there are times when you'll get annoyed. For instance, when you get hit, you don't lose hearts or health, you either get knocked back or suffer a status effect (which can be a blessing and a curse, since some status effects can aid in progressing through the game). That makes the game incredibly easy but at times irritating. And those times are mostly with bosses. Bosses are theoretically easy, hit em 3 times in a soft spot and they're done; however, get hit once and you get knocked back out of the boss area and have to make your way back and start all over again.
Yet as irritating as the boss battles are, they're still easy. Even with repeated attempts, it never took me more than 15 minutes to reach and defeat any boss. Imagine how quickly you can unlock a chest when there isn't a boss.
Sound is ok. Sound effects could be better. Music is pretty good. I wouldn't really know since most of the time i play with the volume off (i usually whip out the GB on breaks at work).
Overall, great game. If you've got a GBC or Advance or whatever, pick up this game. Well worth your time.