I used to be a member when I lived in London - didn't really take advantage of it as much as I should have though (bloody kids). They show a vast range of films so can't really tie it down to a particular type. Best thing I saw there was Alien in 70mm.
Also had a subscription to Sight and Sound in the past - it's a good magazine but it's not one you can read thoroughly without having major plot points revealed as they provide a full synopsis with each review. But it does have some good articles and interviews if you're looking for something a bit meatier (or less tainted by the need to lure advertising revenue) than the likes of Empire or Total Film. Nothing wrong with those mags if that's what you want but it's a BBC 4 vs BBC 3 situation. As above I'd definitely check it out with a couple of single issues before subscribing.
Don't say it didn't... it did!