If you want to go in to watching this film without seeing the trailer, then don't read any reviews - including this one. There are no spoilers beyond what the trailer shows.
I make that opening claim because if you hadn't seen the trailer, you wouldn't know of the dual-genre nature of Overlord. The genre shift to full-blown 'zombies-but-not-quite' action comes after 75 minutes of truly brilliant wartime drama with some moderate scares. The opening scenes of the paratroopers entrance to the war-torn French countryside is a particular highlight for its chaotic, intense and disorientating depiction of what it must've been like for those who did the deed for real in WW2.
The horror element begins to build early on but is never an indication of the upcoming genre shift (if you've not seen the trailer, at least) until the point (From Dusk to Dawn style) where it's made clear that we're not in Kansas anymore. The only bummer I can think of is the film falls into the trap of a predictable final 30 minutes. With all the enjoyment had before then, it's so disappointing to feel let down at the last hurdle.
The soundtrack is immense, the cinematography is brooding without being dark (a style which works for both of the film's genres), and the CGI special effects are affectingly convincing. Don't expect great things from the script (which includes several awful one-liner comebacks), but I think this film will go down as one of the great zombie films of recent years, and may even be noted for its even better turn as a war film.
Best quote: "What is this?!" - "Our greatest achievement. With it, we create super-Nazis; a thousand year army and it's thousand year soldiers."
