Yes!!!
When doing color I use it almost every time. I find it much, much quicker, to simply sample my colors from outside sources rather than try to move around in a color wheel.
But frankly, I never understood why there were so many windows for the color options. Why not have them all in one longer window... Actually, I rarely use the others, just the first color window (the one that opens when you click on a color in a node) and the color window your asking about now.
It would be nice if the color sampler were in the first window at least, though. As it is now you have to close out two windows after preforming a single action... It gets annoying when working all day.