I too am a little worried about it messing up my teeth, but since I got a new one yesterday, have not taken it out of my mouth. I do think this is probably the longest I have gone with one in my mouth.
It is very soothing, and when I go to sleep with one in my mouth, I sleep a lot better (quality, not quantity - I don't sleep more than five hours normally).
I kind of like the fact that I can't talk to communicate. And although today is the first time I have really experienced it, the fact that I can't control dribbling is strangely comforting.