I read previously that the ball loses a lot of air, but I can not confirm. He actually lost a little, but it seems to be only a limited volume, I have not inflated the ball for two months, and sit on the same level as 2-3 days after inflation. The ball has smelled from the beginning not overly Rubber, just a little while unpacking. The smell, however, disappeared long ago. Otherwise, the ball is definitely not a perfect sphere, but somewhat flattened.
It's a little difficult to remove the plug if you want them pumping, but is supposed to get stuck. Another closure system might be more practical.
What I can not judge, is the stability, if below it pointed objects. As I look out from the outset.
Conclusion: Would buy it again at any time and definitely not give up.