After having read all the threads on the buggy state of the game I had expected the game to be unplayable, but a friend recommended that I give it a try anyway so I figured for £3.50 it was probably worth it. I have to say I was almost immediately drawn in by the game, something that very rarely happens to me. I think I must have spent an hour just wandering around the starting town before actually getting anything productive done. I haven’t encountered any bugs yet, though to be fair I'm still in the catacombs.
The one question I had was that I chose a survivor for my first character and so far he appears to play pretty much like a warrior. Do skills like prowling and lockpick become more useful later on? Still that aside it seems like a great game, the kind you just don't see any more.

Well . . . you ARE going to run across some bugs . . . soon. The patch is supposedly being tested for release so you won't have to endure the bugs long . . .=)
I managed to play thru to the end even with the bugs but my install seemed to have fewer game stopping bugs than most. I did have all the usual, spinning monks and unusable statues, etc.
Having said the above, I agree completely with your observations, it has a unique atmosphere, music and story along with some great game play. Not many like it.
Yes, lock-pick will be very useful later on, also prowling and all the other skills to one degree or another depending on your character build.

i played as a survivor too but only used the sneak function a couple of times, mainly to avoid some CTD bugs. Lockpicking is a useful skill to have but don't go overboard too soon.
The only quest I couldn't complete was the Church although I did have the odd spinning character and a few things I couldn't pick up, nothing too bad from what I can gather.
There are some fights later on that will cause a CTD, I found that using ranged weapons, even at point blank, seemed to cause less problems in these instances.

I too ran the game flawlessly for a long time and was scratching my head at all the bug complaints. Eventually, though, farther down the main quest I ran in to several show stoppers. Had some on some sidequests too. They all happened consistently so I put the game on hold.
Like Stuff says, though, the patch is currently being tested as we speak, and I can't wait! This game sucked me in for all the reasons you mentioned. It's one of the best computer wRPGs I've ever played, honestly. I'm really happy with the purchase.