The MOTOACTV has limitations. It's water resistant, but not waterproof. That means you can't use it while swimming or doing other aquatic exercises. While individually the various functions of the MOTOACTV require a comparatively small amount of power to operate, collectively it can be quite a drain on the battery. That means if you're training for long-distance running or cycling, the battery may not last for an entire workout.
Upon launch, the MOTOACTV could support about half a dozen different types of workouts. But with firmware and software updates, this number could increase over time. It's also possible that Motorola could introduce support for a wider array of sensors if there's a strong enough market response.
Can a device like the MOTOACTV help you lose weight? Studies indicate that people are more likely to follow a proper exercise and diet regimen if they keep a record of their activities. It may help with motivation and focus, preventing people from falling out of the habit of exercise. And MOTOACTV also allows you to set up competitions with real or virtual exercise buddies to keep you on your toes.
Ultimately, weight loss and fitness requires you to do a lot of work. Buying a device won't guarantee that you'll shed pounds or build lean muscle. That's going to depend upon your own efforts. But when you have hard data to help you keep track of your progress you may just find the inspiration to achieve your goals.