It's been pointed out by others that this game is a mish-mash of cliches. The protagonist, Rayne, is a half-vampire, secret-agent, nazi-fighting pin-up girl. The game, and the heroine in particular, has a decidedly juvenile tone. These things sound like they would make for a bad game, but the developers never seem to take things too seriously and as a result the whole thing ends up being a lot of fun, albeit with a tinge of guilty pleasure.
Bloodrayne is a 3rd person actioner mixing melee and guns. The two aspects are nicely balanced and both have their uses. Nothing too groundbreaking gameplay wise, but the levels are nicely varied and it maintains an acceptable level of fun thoughout.
Get it. Play it. Have some fun then set it aside.