I have been following the Underworld Series and have been looking foward watching the 3rd series which is the UNDERWORLD (Rise of the Lycans).
In this movie, it was thoroughly explained how it all began. Why Lycans and Vampires hated so much. If you noticed, in the first series, there were past scenes where you saw Sonja.
All in all, I love it and its yet another vampire exhilarating movie.