I have always HATED vocal booths, and always record vocals in a large acoustically treated room if possible. There is nothing worse than taking a performer who's basic function it is to get out on stage, jump up and down and yell at the the top of his lungs, and put him in a little constricting, claustophobic space.
If you are a in a project studio with marginal acoustics, try a new product called a Se Reflexion Filter. I found that it works surprisingly well in controlling what goes into the back of a multi-pattern mic when recording vocals, really helps to focus the singer, and lets everything hang out in free space, so that everybody can BREATHE....
- h.