Well, as I mentioned in the Happy Thought thread, mine arrived this morning. It's a rather weird feeling, but doesn't take too long to get the hang of it & keep it going. My arms ache a bit, due to it being rather addictive.
The thing I'm not so keen on is how bright the lights are, but it's not really a problem to just shut my eyes, as you don't need to look at it once it's spinning - the important thing once it's spinning is the way it feels. It's kind of like swirling water round in a bucket by actually moving the bucket, rather than using something to stir it. Once it gains momentum, if you stop putting so much effort into moving the bucket, you can feel the water trying to move the bucket. The feeling you get when trying to keep a Powerball going is rather similar to that.