It was worth seeing Underworld 3 for the crazy compare/contrast between Michael Sheen as long-haired Gladiator-style werewolf leading all the other wolves to rebellion against the effete vampire nobility, and Michael Sheen as slick 70s talk show host with posh British accent in Frost/Nixon.
Meanwhile, Frank Langella had morphed into such a doppelganger for jowly Richard Nixon, it was halfway into the film before it occurred to me: hey! He was once the sexy young Dracula. Which actually makes this an epic smackdown, werewolf versus vampire style!
If they had CGI'ed into their respective creatures of the night, how much more interesting of a take on the subject it would have been than the Underworld mythos, alas. But it was still pretty interesting, despite their remaining in human form.