I haven't tried botox (or the BrowTox), because as of this point, at almost 46, I do not have any forehead wrinkles or even any fine lines up there (don't be jealous, I have "other" issues...like drooping upper eyelids and the start of jowels...ugh). I'm planning on getting Botox injections when I do start to notice forehead wrinkling though.
I have a close friend who has it done and she's had very nice success with it (she's only 37, but she's got a fierce case of 11's between her eyes). There was one time she got it where she got too heavy of a dose and it caused her eyebrow arches to droop, but it got better as it wore off and she just has less injected now and hasn't had that problem again. I don't think it causes worse wrinkling if you stop using it, just that you look worse because you were looking so good before. You're supposed to have it every 3-4 months and the more/longer you have it, the better the wrinkling gets.