I loved Underworld. But I love most decent Vampire or Werewolf films, so that's a bit biased, eh? Basing the two species on a genetic, scientific idea makes them work exceedingly well, and removes all those problems that mysticism brings to a film, like reflections or holy items. This Vamp-Werewolf model make explanations easy, rather than requiring long prologues or in-depth discussions. The whole 'virus' idea is logical, and easy to follow. It's slick, modern, fast-paced action combined with classic, Gothic Vampire & Werewolf ideas, like the Vamp's high-tech weapons being kept in a massive, stately manor. I'm a real fan of the whole colour scheme, with few colours used in any one shot, and blues used for almost everything, keeping it looking cool, and sleek. I am also a Kate Beckinsale fan, and I love Action films that don't use women like an extra person to shout 'watch out!' or hit someone over the head. K.Beckinsale's character is great for this, it's someone who could easily be a guy. (Although, I'm thinking the outfit'd need a bit of enlarging if it were)