Here's a third-installment prequel to a scifi/horror/action franchise dedicated to the retelling of a backstory that was previously told to completion - along with all relevant details - in a two-minute flashback in the first film. If that's going to bother you, don't see it. If it doesn't - i.e. if you're an "Underworld" fan or a genre-fan in general and thus have been down this road before - you can do A LOT worse.
What I like best about the improbably-good "Underworld" movies is that it's a franchise wholly of and about itself - a rare feat. It's not based on or trying to pay fealty to some previously-published material and (even better) it's not trying to be in any way bigger than it's own story and world: Here's a trilogy (and counting?) about a centuries-long war between Vampires and Lycans (Werewolves) that never makes a move in the direction of social commentary, metaphor or even genre-deconstruction. It's Vampires aren't AIDS metaphors or wink-nudge abstinence advocates - they're pale, fanged, blood-drinking immortal aristocrats. It's Werewolves aren't stand-ins for puberty-angst; they're giant hulking wolf-headed monsters.
The two "later" films were futuristic and sprawling, this prequel is (literally) medieval and limited to a handful of locations centralized around a single Vampire fortress - in fact, it resembles nothing so much as a BBC 'royal manor' soap opera by way of the Universal Monsters. The story primarily concerns the hero-journey of Lucian (Michael Sheen,) the memorable Lycan rebel leader from the first film, here originating as a slave (the Vamps use the Lycans as brute laborers, the two races are technically cousins but the Vampires seem to be better about money) who's picked up a yearning to breath free while coverlty fooling around with the King's daughter Sonia. Sonia is embodied by Rhona Mitra, the amazonian Irish/Indian beauty whom you'd remember from "Doomsday" if you hadn't ignored it in theatres but probably know best as Kevin Bacon's unluckily-attractive neighbor from "Hollow Man."
What you ultimately get is mid-budget, feature length "seige of Helm's Deep" with armored, sword-wielding vampires standing in for the humans are werewolves standing in for the Orcs. I'm perfectly happy being among those for whom that spells "worth a look." Oh, and you also get Bill Nighy, who doesn't really NEED to act in this but does anyway. Good on him.
Small footnote, though: Warner Bros./DC Comics? If you're looking at ANYONE to play "Wonder Woman" OTHER than Rhona Mitra... can I ask why?