Not much here, except a prettier package and "extended" footage. By extended, they mean a couple of shots of people walking around doing nothing, some exposition heavy dialogue between Michael and Selene, a scene with the blonde vampire who kinda looks like Julia Stiles, throwing herself at Kraven (btw, what ever happened to good ole fashioned nudity in R-rated films? It's perfectly fine to decapitate someone on screen but heaven forbid you see a boobie) and a genuine kiss between Michael and Selene. My eyes glazed over the rest. The bottom line is that the extra footage was cut for good reason. The "Fang vs. Fiction" documentary aired on cable a couple times ("I'm a real vampire! Look at my fangs!"). The commentary from Scott Speedman, Kate Beckinsale and Len Wiseman is pleasant enough, but not a lot of insight for screenwriting geeks like myself.
I saw an interview with Wiseman and wifey Beckinsale talking about the sequel, "Underworld: Evolution". He promises more action and gore. A little hand to paw combat would be nice. Hopefully, they've done a better job with the werewolves this time around so they don't look like shaved hamsters. We'll see. If I'm not mistaken, it's supposed to be released in December. Nothing like a little Christmas cheer to put me in the mood for a horror movie. Good luck against the Narnia crowd.