Mediocre at best
Gameplay: At first, there is some fun behind Wario Land 4. The controls are easy, and the stages aren't really hard either. But it gets boring doing the same thing over and over again.
Graphics: Typical GBA graphics.
Sound: Not bad I suppose. Nothing really special though.
Needless to say, I'm left unimpressed. It's your average "go through the levels and beat the boss" game. One of the few original concepts of Wario Land 4 are the minigames, which are more of a chore than fun. You need to play them to win medals, which are the currency if you'd like to buy items to make boss fights easier, which is nice, but takes away some from the enjoyment of the battles.
All in all, unless you are a diehard Wario fan, just pass on this one. It's okay, but after a while, you'll get tired of it.