Pros: Was a gift for me for Christmas and it does make your forearm strain .

Cons: none

Other Thoughts: Kids wouldn't let me read history until now so I wouldn't see it.
Works great

Pros: LED lights work quite well on this product.
Once started, smooth operation.
Shell material feels good quality plastic.

Cons: Not so easy to start - have had to use the supplied strings every time, though supposedly you should be able to start it by hand.

Other Thoughts: It seems a little expensive compared to other similar products on the market, but since I haven't used those I can't really compare.
My only concern with this is, how long will it last - it doesn't sound very smooth when starting up (although once it's going, it doesn't make much of a sound).

Pros: Smooth and balanced
Changes colors red -> blue
The purple tint of the gyroball does not affect the LED lighting

Cons: Kind of disappointed. The NSD Power -- Rainbow is not actually rainbow. It has 2 color LEDs, red and blue. The first level is red, second level is red and blue (which I'm assuming is suppose to be purple, but the colors don't mix well at that speed), and the last level is just blue.

Pros: Love the colors, I use it every day and I feel it working.

Cons: To get it started is sometimes difficult.