Mainly a music venue or awful night-club type place, I've definitely been to the Purple Turtle in the dim and distant past just for drinks and meeting friends for a night out - and not having to pay to get in, ie. like a normal pub, or rather bar. I think it might have been in its previous incarnation as the Kao Cafe, but this was nearly 15 years ago so I can't really remember.
I've been back since for gigs, and they've been good. But that's all it's good for really.