The werewolf / vampire fan says:

Rating: Null/10 (3 July 2004)

I went into Underworld hoping to see a great, classic match up between werewolves and vampires, and instead got an annoying bore fest. Hardly passes as an action movie, as well... or at least that's what Blockbuster likes to classify it as.
The werewolves looked... well, they didn't even look like werewolves. I can recall the director saying on the DVD commentary that he "aimed for the muzzles to look cat like," which was an obvious mistake, in my opinion. I mean, come on... they are werewolves, lycans... not werecats.

As for the vampires... they were displayed as what seemed to be helpless throughout the first half of the film, which really tended to get on my nerves if anything. And just for the record... vampires are NOT supposed to have reflections. Big no-no.
In closing, Len Wiseman attempted to give the world a new, updated look upon vamps and wolves, and ultimately failed. I give Underworld a 5/10 for the mere fact that no CGI was used on the lycans, it was all done with costumes and wires. That certainly is a plus, I suppose. =P