I was on only 10mg once a day for anxiety, for over 2 years though. They did the job, but I found that I have become a lot more insular since i've been on them, also that if I am having problems facing up to certain situations then I think I would rather find ways of dealing with that problem than masking it with drugs.
I have found relatively simple breathing techniques help quite considerably in managing panic attacks, if only Dr's would teach these to people before reaching for their prescription pad.