It has a good cast and a good plot.
It's a vampire movie (I see some of you gasping in shock ;)) with some kick arse females and some very nice looking chaps too ;). Basic premise is that Rayne, a Dhampir (half human/half vampire), who saw her father (the big bad vamp played by Ben Kinsley) murder her mother, is out for revenge. There is a society called Brimstone out to kill the vamps, but the vamps are winning thanks to their human servant army. Rayne and Brimstone join forces along with some subplots along the way.
The plot holds together with some nice vamp lore and although the ending is a bit meh, it's still good.
I have just ordered BloodRayne 2: Deliverance, we'll see how the sequel holds up.