I'm busy playing through it at the moment. I started about two years ago, but the hardware I had at the time meant slow (and frustrating) frame rates. With the current rig it is pretty smooth, so I'm back playing (as a Ventrue).
But yes, buggy as H*ll. Not just the big stuff, either. The only quest problem I have had was the hidden camera one: I got in and out (on about the twentieth attempt - boy, that boyfriend is alert!) without being detected, but the quest-giver thinks I was detected, so no reward. No, the main annoyance is little things like: if you run into a door while it is still opening then you get stuck in it, or else it just shuts again. And often boxes etc won't stay open so you can remove the contents. The AI is pretty basic as well.
But because Troika went bust there are no more official patches, and I'm not keen on all the changes in the unofficial ones.
The game is interesting to me, because I have just come from months playing Oblivion, another first-person Action-RPG (which reminds me, the fact the Bloodlines drops to third-person whenever you fight is VERY annoying), and it is a rather different experience. My main disappointment about Bloodlines is the fact the being a vampire is almost irrelivant to the game. It supplies the plot, but has no influence on game-play. It is never day, so that is never a worry. Sure you can regenerate health, but you can do that in loads of games. Blood id just mana/magicka by another name. Feedijg is really the only true vampire bit. What would be great is a cross between Oblivion and Bloodlines, with the open-ness of Ob, combined with being a proper vampire. With daylight to be avoided, blood to be found, people recognising you and shunning you (almost no-one seems to see the fangs in Bloodlines) etc.
But still an under-rated game.
M