Halfway through, the gameplay takes a sudden nosedive into a Doom-style run through a maze of sewers, fighting off hordes of creatures. To make matters worse, there are only two major different enemies in the sewer sequence, although a third type appears eventually, its presence is decidedly unwelcome. The game rebounds from this and still has a few interesting scenes left, but it never regains the charm it had at the start. Incidentally, here's some free advice: Ventrue characters would be wise to be conservative with their powers in the sewers, as non-rat blood sources are few and the sewer run is much, MUCH longer than you'd expect.
Although nothing that follows is quite as bad as the sewer run, there increasingly more levels in that vein as the game progresses. This is in rather stark contrast to the nice mix of social interaction and combat that pervades the early parts of the game.
Obviously the game design issues are the most serious problem with Bloodlines, though they're not the only thing wrong with it. In fact, while it's possible to forgive the game design drawbacks (if not tolerate them), we can't forgive the bugs. We've heard numerous times that Vampire has been done for a while and it was only waiting for Half-Life 2's release due to contractual obligations. Although no software is bug-free, a game that's been "finished" for 6 months should run a lot better than it does.
For starters, Vampire's performance is awful compared to Half-Life 2, a game it shares an engine with. My Pentium 4 3.0C with 1GB of RAM and a GeForce 6800 Ultra Extreme would have more than the occasional hiccup at 1024x768 and no AA/AF, while Half-Life 2, a game with higher-resolution textures and more visual fidelity, runs almost flawlessly at 1280x1024 with 4X anti-aliasing and 8X anisotropic filtering. A lot of this is likely due to memory issues - both in terms of the extra roleplaying info the game has to carry, and a persistent memory leak that degrades performance as gameplay goes on - but it's not excusable considering the review system runs a gig of RAM.
For all this poor performance, Vampire doesn't really look that good. Animations are... wacky. We wonder if they were even motion captured, rather than animated by hand. The way male characters run and walk is rather disturbingly feminine. Facial movements, a highlight of Half-Life 2, are odd in Vampire as well. In Half-Life 2, the entire face would move. In Bloodlines, only the mouth and eyes are animated, it gives a rather stiff look to the face, though generally far superior to almost any other game.
Troika also was obviously unable to replicate the movement physics from Half-Life 2. Your character has this nasty tendency to slide forward after being stopped, making the obnoxiously loud footstep sounds the whole time. Also, physical interaction with the world is on a far lesser scale than HL2, and buggy when it exists. Just try picking up a piece of plywood or other flat material, laying it on the floor and then walking across it to see what we mean.
In general, Vampire: Bloodlines is a lot like Deus Ex: Invisible War. You unlock various levels and are able to access some of them later on, you start in the middle of a story with competing factions involved, there are multiple solutions to most puzzles, side-quests galore, plenty of NPCs to talk to on multiple occasions ... and performance is disappointing with both games.
They both have interesting settings, but Vampire does have the better, tighter story, along with more humor. Unfortunately, Vampire comes to rely on combat a lot more than Invisible War, and gives the player much less freedom of action as the game progresses.