As a single player game, it preforms admirable, but the "multiplayer" part is severly lacking.
What really drags the game down is the "multiplayer" part. the wii is a family console and invites more than anything to competition and multiplay. BBA for wii has three multiplayer games, yes, but only one of them allows for more than one controller. The two others are based on "teamwork", where you hand the controller over at different intervals.
Mental marathon is okay, you play a mix of mini games until one answers wrong, but are you several player will you spend most of your time sitting and watching the others answer.
Mind sprint allows for two controllers, and will be fun if it's either played by two players (one on each control) or a bigger equal number. But the game fails heavily when you have odd numbers. You can play up to four persons against a "player book" (pre-recorded effort by one of the players), but while your team have to change person playing, the player book just keeps playing, so to have any chance winning, you have to fling the controller to the next person as fast as you can, and answer questions at atleast double the speed of the computer.
Brain quiz gives you a board of different challenges, where you chose which specific game, or category you'll play. The game randomly picks the hardness level you have to compete against, from easy to expert. And here the problem lies. You don't get more points doing a hard game than a easy game. Your score is based on how many correct you get, and the only thing thats different with each skill level is how much time you have to complete it. Therefore is easy over much to fast to fetch any real points in, and experts so hard that you'll probably only manage two or three anyway. Medium is the best difficulty to get, and who wins is defined by who gets the most medium, and how good you're in the 2x score game you get.
The game is fun as a one or two-player game, but fails to offer family fun. The randomness of several of the multiplayer games also makes the game experience more frustrating than funny.