Funny, I just started a thread last week in IMHO talking about how bad I thought this movie was 
http://boards.straightdope.com/sdmb/showthread.php?postid=4457235#post4457235 (sorry, I don’t know how to dumb it down)
I didn’t mind the concept and storyline…werewolves fighting vampires is a cool idea and could be done really well, and the idea of what the werewolves were trying to do with Michael was pretty interesting as well, although I wasn’t quite sure what their motives were. Having played and enjoyed Vampire: the Masquerade, I thought it worked pretty well, but I didn’t like the weapons used by the werewolves…i thought that was a silly idea, and really much rather enjoyed watching the big galloots chomping and tearing their way threw the enemy.
What I really didn’t like about it was the science…(spoilers for anyone who hasn’t seen it). According to this, “on the cellular level”, vampires and werewolves can’t co-exist. I remember Selen mentioning to Michael that, seeing as how he was already bitten by a werewolf, if she were to bite him, he’d die. This means, any vampire who bites a werewolf would die because they’d ingest the werewolf’s blood, and the werewolf would die because of the “bacteria”, and vice versa. That’s just dumb. Also, apparently not everyone can be turned, because a simple bite infects, and the infection, as she says, is almost always fatal to a mortal. This bugged me because it seems like vampires are still able to sire whoever they want…but if the bite of an immortal kills a mortal, then how can you sire anyone?
The phosflorescient bullets were just silly, and the explaination was sillier. “It’s liquid sunlight.” WHAT?
A vampire vs werewolf movie is a great idea, this just wasn’t the best execution. Maybe the sequel will be better.
A question about the ending, for anyone who’s seen it…now, from what I got, the mixing of pure bloodlines can create a super werevampire. They used Michael to create the pure werewolf, and the elder vampire lady to get a blood sample pure enough to merge and create their “secret weapon”. At the end of the movie, you see the dead werewolf lying on the floor over Marcos’s tomb, the blood flowing down, then Marcos’s eyes opening. Then they turn black. Now, he was apparently a direct decendant from the original vampire, thus one of the “pure bloods.” Did his ingesting the werewolf blood simply wake him up, or turn him into an abomination as well?