The concept of Underworld was great – probably the most interesting version of the vampire/werewolf mythos to be produced in a long time. The basic outline of the plot is also very well thought out and some of the individual elements of the production design indicate that they were really trying to create a serious movie (Romeo & Juliet derived though which is a black mark against it in my book).
They had a great idea, they had a great plot, they had good initial character designs and a great concept behind the supernatural aspects of the movie. The problem was that they did a really lousy job of bringing all of these great things to the screen.
The acting is all over the map, from well-done to absolutely awful. The dailogue sounds like it was written either for or by a 12 year old. The vampires are so gothic as to be parodies of the gothic (the costuming director needs to watch fewer Tim Burton movies). The werewolf special effects are embarrasingly bad (they’re not hairy so much as they just have really dark colored skin and only a little bit more hair than a person). The production design is inconsistent and seems to me like they ran out of money part of the way through the production.
As for objectionable material, there is violence and there is a little bit of gore. Some foul language too. I don’t remember anything sexual, but honestly, I didn’t like the movie enough to remember that much detail. It’s worth a rental if you can look past the objectionable stuff. If you can’t, you’re not missing much.