Profoundly average. There's nothing really to dislike about it, but you've seen these gameplay mechanics so many times before the game boils down to going through the motions and seeing Animaniacs cameos.
Anyone older than 3 that picks this game up for themselves should really have their head examined. The reason is simple: Animaniacs is a child’s game through and through, but the gameplay is way too frustrating for the intended audience.
The password system, the lack of detail in graphics and sounds, the annoying controls... I honestly can't even justify playing the GBA game on the DS, much less the DS port of it (which only seems to add a multiplayer tag mode).