I used it with my twins last year and thought it was bloody wonderful. Parents need time off too. My kids didn't want to leave when I went to pick them up. And they asked to go back the next night. I found the CMs very reassuring.
The fact is Disney is a lot of standing around and waiting in a line. Its gets old for kids too. They need time to unwind, do some imaginative play, have some free play, interact with other kids, etc.. It frees them from the regimentation for a little while.
Questions to think about: Does your child separate easily at school? Is she completely potty trained?
There is also in-room babysitting if the above is negative.