The balance board itself is a lovely bit of kit; roughly the size and shape of a luxurious set of bathroom scales, extremely solid, and connecting wirelessly to the Wii. It runs on four AA batteries, and mine is still going strong after a good week of use. The board seems able to read where and how much pressure you're putting on it across the whole surface, enabling Wii Fit to work out whether you're leaning in one direction or another, whether your heel or toe is taking the most weight and even your current centre of gravity. It might not look like much, but it's a more sophisticated and sensitive peripheral than you might expect. What's more, Nintendo has imbued it with extra personality by making it a character in the game itself, acting as a host throughout Wii Fit's option menus, and even pleading with you not to stand on it during its short calibration routines.
With registration over, we're onto the good stuff, though it must be said that Wii Fit is a slightly schizophrenic affair. On the one hand, it has all the worthy stuff, comprising a series of Yoga exercises and a selection of workouts designed to improve your posture and build muscle tone. You stand on the balance board (or in some cases, squat or rest your hands on it) then follow a stylised instructor as he/she takes you through moves then repeats them while you copy. It's all very nice, thoughtfully done and unthreatening, and you can choose whether you'd rather work with the guy or girl instructor (I suspect gender and sexual preference will make this decision for you). At the end of each exercise you're rated depending on your movements and your balance (to the extent that the balance board detects them) giving you an idea whether Wii Fit thinks you are coordinated or a clutz.
After a week or so you probably will feel some results from these exercises, but if this was all there was to Wii Fit then I'd have probably packed it off to the novelty cupboard by now. The sugar coating that makes the medicine go down comes in the assortment of balance and aerobic games that put the balance board to more entertaining use. With your Mii now centre stage, you can take part in slalom skiing, ski-jumping and football heading activities, not to mention hula hoop spinning and step classes, all powered by various combinations of walking and leaning. Suddenly you're a human joystick, frantically stretching left and right to catch wide balls or get through the next gate. I don't even want to talk about the gyrations involved in the hula hoop games, except to say that if a video ever ends up on YouTube then I might not be responsible for my actions. All in all, it's the sort of simple stuff that made Wii Sports and Wii Play so instantly engaging, yet the fact that you're still thinking about balance or that you're still involved in a physical activity means that the game is still doing you a little good.