For a start, posters which appear to ape 300 and Tomb Raider mark it out as derivative, even while it is playing the 'innovative' card with all this mocap stuff.
That's just marketing, to my mind.
300 was a big hit, and anyone who liked that is likely to like
Beowulf, so I don't really blame them for drawing on that.
Seeing clips, though, I'm not sure what the purpose of the mocap is. es, for Gollum. But getting humans to act out and then cgi-ing them up to look like humans...erm, why? The clips I saw looked like a cut scene from a video game, and I'm not sure I could stomach 2 hours of that, although the reviewers on NR were quite enthusiastic about the animation, they had problems with the story.
The purpose of mocap is for the things that aren't human. Sure, you could film Angelina Jolie in a body suit and it'd look pretty similar to what we get on-screen, but her tail would contrast with the live action more, as would the other dragons and demons that have to fight alongside the mo-capped humans.
As for video games...there are a few shots where it looks like one, sure. But not many. Typically, in digital productions, they look worse as you move in closer to the characters, and better when they focus on vistas and wideshots. The exact opposite is true here; the closeups look great, and the wide shots are what lack those little human touches that ring true for us.
I was quite impressed by how lifelike the characters look. That doesn't make it a great movie, of course (I just posted a
review, and elected to give it 3.5 of 5 popcorns), but I do think it's a great achievement.