Professional Quality, comes with pump, Nice!
Is a professional quality ball, works good. It comes with a pump and a sizing band so you can and know how to properly inflate it (which by the way was also a good cardio exercise.)

Sizing is pretty accurate
I'm 5'3 and I have been using this ball mainly as an alternative to my desk chair. When I'm at home I use my computer quite a bit and my posture has been suffering because of it. I assumed it would be slightly too big but actually I find it to be slightly too small. But I'm using this as a chair, not as an exercise ball, well at least not yet. If I were to use it for that I'm sure the sizing would be correct. So if you're small like me, this ball is perfect!

Not Getting why everyone loves this....
I don't get it...why is this so popular? I just don't enjoy the workout as much as regular yoga or pilates, and not sure if I am getting any additional benefit.

Strong and pliable
I gave this to my son for christmas and while we don't do a lot of body ball exercising, he uses it to sit on while watching tv. I have found that he thoroughly enjoys it and it keeps him moving even while being a couch potato.

This ball doesn't hold air.
This ball doesn't hold air. I'm not sure if it oozes air from the small hole it came with or the valve. The hole is rather a thin spot (in the already thin rubber )that might of developed after sticking to itself. Not worth the money. I don't think it would pop with average weight put on it.