In English: I love it, the size is small and you can carry on your purse for whatever purpose you have. I like it specially when I want to make a composition on my house decoration or makeup.
In Portuguese: Amo, nao e grande, da pra carregar na bolsa e usar para analisar composicao de cores onde quer que voce va. Gosto disso porque posso ir numa loja e usa-lo para comparar as cores ou para compor minha maquiagem.

I use this color wheel all the time in my sewing. No second guessing anymore about colors matching or coordinating. Easy to understand and travels to my sewing stores in a zip lock back with no problem.

Oh, my gosh! I LOVE this thing! It was just delivered several minutes ago. I spent about 10 minutes with it and feel like I've had an explosion of comprehension!
I realize that color theory must be more deep and complex than this initial introduction (it is isn't it?) but this is clearly the fundamentals--and grasping them and having this tool to guide me has given me an instant confidence in my ability to use color that I have always lacked. I can't get over the wealth of information concisely contained in this little device.
I have, of course, seen the color wheel represented in various books over the years, but somehow this device caused the information to finally penetrate--maybe because it's a dynamic tool (rather than a flat and static page) that allows you to visually comprehend rather than receiving the information only intellectually.
Well, whatever...
But if you feel intimidated by color or just need some back-up, this is an amazing device. I highly recommend it.
May I suggest that you carefully trim its package to open it so that you can retain a sleeve to keep it in.

After constantly being called at God awful hours by other cake decorators who have no idea about color theory, and repairing baby blue cakes supposed to be turquoise...teal...etc., I decided to buy this wheel instead of the advanced CMY color mixing wheel, which would of confused them even more as it is based on the cyan/magenta/yellow primaries. Gonna give a quick explanation on how to use it and it does have basic info printed for reference. Think I will also print out the "Six Ways to Make Brown" on ask.com to cover my bases ;-)

I'm a member of the vast legion of people with no real ability to do graphic design. If the project is important, I always find someone with a good eye and some technical ability to do the job for me.

However, modern software allows us to do quite a bit of graphic design, and it makes doing so quite easy. The result: lots of really bad looking letterheads, WordArt, meeting place cards, etc.

This simple, cheap color wheel allows people like me to overcome graphics-impairment-- at least to an extent. It makes it very easy to figure out which colors go with which other colors. Spin the wheel a little, look at where the arrows point, and select the colors in your software. The result will still be amateurish, but at least the colors won't be offensive...

Bottom line: This is a simple, reasonably prices tool that will help you avoid garish color choices in your graphics. I recommend it most highly.