....Great, a 4th one.
This is coming from a person who has indeed seen all of them as of yet, and disliked all three. Vampires are cool, my only major, major issue is how much blood they do drink. Dunno why, but it became really irritating after awhile when I was in the middle of the 2nd movie and it suddenly dawned on me that Vampire's are heavy blood drinkers, heavy. You rarely see them drink (though there was some in the 1st).
Other than that one complaint, I had not major issues. a friend of mine said she didn't like it due to the blue werewolves in the 1st, but stopped complaining when I told her the guys who did the animation put too much of the filter on top of them, making them blue.
But...all around, a stew pot full of vinegar and the bones of fat of pigs, and that pretty much sums up the Underworld for me....
....Oh, and no, I did not see the Twilight Series, and I don't want to, everything that the commercials showed me let my skin crawl