This Powerball has to be one of the better little items I've purchased for a while. You really do begin to feel it's effectiveness after just about 30 minutes of using it the first time. You know, aching wrists and arms.
It's perfect for having around when you're sitting watching TV, walking the dog, in the car (passenger seat only!) and other situations where you'd basically be doing nothing with yourself.
The torque you feel when it gets to a high speed is very fun, and you do begin to challenge yourself when you get to grips (ha!) with the powerball. Personally I didn't encounter a huge learning curve to getting it going, took only about 2 tries and was not too difficult.
However, as good as this powerball is, there are only two problems with it. This one does not come with a counter, but that is easily resolved by getting a more expensive one to catalogue your increasing performance. The second thing is the noise. It is noticably loud and you'd probably be attracting unwanted attention or annoying others around you unless they're okay with it, or you're in a suitable public place like a gym etc.
Other than that, 5 star item! Definately worth the money.