Nintendo's latest foray into the arena of self-improvement is selling out both in the U.S. and in Japan. There's clearly an audience for combining exercise and fun, but the question is, does Wii Fit deliver? Though the new balance board is a fantastic peripheral and the game comes packed with challenging and engaging activities, the omission of a couple key features ultimately prevent Wii Fit from being the next must-have title.

At the game's heart is Nintendo's balance board, an impressive piece of hardware by any standard. The multiple sensors within the board detect even the slightest shift in weight. For those frustrated with the sometimes finicky Wii remote or the abysmal accuracy of Eye Toy and Vision Cam games, rest assured that the balance board is one peripheral whose fined honed sensitivity you can count on. And with its nearly nine pounds of thick plastic construction, the board is surprisingly strong.

Your workout instructor and the "exercise studio" are nothing to write home about, but they get the job done.

Wii Fit begins by having players select their Miis and use the balance board to "weigh in." Each player is assigned a Wii Fit Age, which is modeled after Nintendo's Brain Age concept, but based on a measurement of BMI (body mass index) and one of several balance tests. It's too bad Nintendo relies so heavily on BMI, a measurement that discounts fat percentage and adjusts only for age and height. As long as more muscular players don't mind being labeled overweight, the Wii Fit Age is at least a useful way to track certain progress. The game also comes with a Wii Fit Channel, which appears on the Wii dashboard and allows players to run their daily body test and track progress without having to load the game disc.

As for the meat of the experience, Wii Fit offers plenty of variety and challenge in the form of about 50 different activities. The exercises are split into four different categories: yoga, strength training, aerobics, and balance games. Though this seems like more than enough to choose from, be warned that most of these activities must be unlocked by accumulating Wii Fit Minutes, earned after completing each exercise. This means it'll be about six hours before you'll have access to all the activities. Many of the strength training exercises also have multiple difficulty levels, with more reps becoming available as you successfully master the exercise. This unlocking structure is definitely geared towards regular, limited Wii Fit use. If you exercise for twenty or so minutes each day, you'll always have new activities to try the next day.

The exercises themselves are surprisingly challenging, even for players who are already quite fit. The yoga and strength training are definitely the more "serious" offerings, placing you in a plain studio setting with a virtual trainer (male or female, depending on your preference). The trainer models proper form and timing, while giving you encouragement, tips, or congratulations, depending on your performance. The fifteen yoga poses range from the most basic Warrior position to the frightening Shoulder Stand. There is equal variety in the strength training: 15 exercises from the simple torso twists to the exhausting push-up contest. In fact, our only complaint with the balance board is that the grip texture can be tough on the palms for long push-up sessions.

Many of the yoga and strength training exercises are made more challenging and interesting by the addition of breathing rings to guide breath control and the balance tracker. This simple element, possible thanks to the acute balance board sensors, shows you exactly where your weight is positioned. Suddenly, standing on one leg for the Tree position is infinitely more rewarding as you focus on aligning your balance as perfectly as possible.

In the aerobics and balance sections, Nintendo provides some more color and excitement. The generic virtual trainers are replaced by other Miis on your system, who populate the world around you. They cheer you on while you run, toss hula hoops, and sometimes even exercise right along with you. The step aerobics - a simplified Dance Dance Revolution using the balance board as a step - is practically begging to be made into its own full retail game. The running, where you hold the Wii remote instead of jogging on the balance board itself, takes your Mii through a colorful environment, where other Miis and barking dogs encourage you down the path. Among the balance games, the table tilt is a real stand-out. Using slight shifts in balance, players guide balls through a series of paths like those old-fashioned wooden labyrinth toys. Navigating the paths quickly and trying to beat your previous times is a surprisingly fun task.

Despite the strength of the individual exercises, Wii Fit falls well short of being a finely-tuned workout device. Blatantly missing is a tool to create a customized routine by stringing together multiple exercises. It takes about 45 minutes to complete a half-hour workout, thanks to the awkward effort required to navigate menus between every single activity. At the end of an exercise, players have to fetch the Wii remote, hit the A button through three result screens, then cursor over to select their next exercise. It's definitely less streamlined than it could have been had Nintendo provided a method for selecting 10-15 specific activities in a row or one of several pre-designed routines.

The rhythm-inspired boxing game is one of the lively and challenging offerings in Wii Fit.

Wii Fit does allow you to track non-Wii Fit workouts like running, dancing, or even doing laundry, and you can set a BMI goal and monitor progress towards it. But the extra features end there. You can't compete head-to-head in any of the mini-games, you can't design your own workout plan, and you can't even set up a single session of exercise. If you want to spend six hours doing lunges, you can do just that - even though fitness professionals would unanimously recommend against it.

In terms of graphics and sound, the title is what you'd expect from a Nintendo game marketed towards the casual audience. The Mii characters and environments are vivid and fun, though sparse on richness and texture. In the yoga and strength training, there isn't much to look at. Your "exercise studio" is plain as can be and the trainers are serviceable, unadorned, models. The voicing is actually quite good, though delivered through closed, unmoving lips. But their tone is calm and encouraging instead of irritatingly motivational, like the trainers in most workout videos. The music is also par for the course in the new Wii/Mii genre. It ranges from unobtrusive and uninspiring to catchy, but repetitive rhythms. Like the graphics, the audio offerings of Wii Fit aren't exciting, but shouldn't ever distract from the task at hand.

Overall, Wii Fit is a good entry for Nintendo's exciting new peripheral. It offers plenty of fun and challenging activities that effectively show off the balance board's capabilities. As a fitness tool, however, it leaves much to be desired. Those looking for a fun party offering have clearly come to the wrong place, while others that want a good workout will no doubt look forward to some improvements should Nintendo ever take a stab at a Wii Fit 2.