I was really impressed with this after the first uses, however with time my hair actually doesn't look any better. It gets greasy just as fast. The only plus is the wavy look and the protection you get from constant rubbing. As other users have pointed out, the silk leaves a knot on your forehead, tends to slide off, especially if you're trying to keep it higher up to avoid the mark on your forehead (vicious circle!), and can sometimes be a bit painful. I was very skeptical at first as I need to be really comfortable to get a good night sleep, but actually the slip is not so uncomfortable as to wake me up. In my case it doesn't slide off often (it's happened only once so far), but you should be aware of those little things. I think next time I'm going to invest in a silk pillow though it won't be the same.
I wash my slip in water, would NEVER dry clean it as it touches your face, is close to your nose, and breathing all those chemical CANNOT possible be good for you. But you need to wash it often, once a week is a must.
All in all, not bad, but not sooooo good that I would recommend it enthusiastically.