I've been here a couple of times now, it is a great gimmick bar, and definitely worth taking those friends/family that visit from outside of the M25.
Drinks are indeed pretty expensive unless you can stretch supping on the one drink included in your admission price (£14 if i remember rightly).
On my last visit I stupidly placed my drink onto a table, choosing to ignore the oil slick from someone else's drink, and so my "ice glass" slid off the edge of the table and became part of the interior....foolish as I didn't realise until I approached the barmaid that a replacement glass cost £4 (£10 for a 2nd drink and new glass!), however.......They do keep a rather large stash of fresh cut glasses to one side of the bar, so if you have a willing band of merry men...you can successfully "discover" another glass rather quickly....I obviously did not do this....and wouldn't suggest anyone else attempts it....
Anyways - definitely worth a visit early on in a west end evening.