My main (and only big) problem with Bryan Singer's Valkyrie is the same problem I have with "movie stars" in general. For example, I believe that Tom Cruise is a very fine actor, or at least a generally underrated one, but since he's a Movie Star before he's an Actor (and yes, he is), I find it almost impossible to LOSE him in a role. Sean Penn gets lost in a role. He just vanishes! Johnny Depp does it a lot, too. (Or at least he used to before the Pirate flicks came along.) Julia Roberts as a Victorian Queen is still Julia Roberts to me, which is why I prefer those chameleon-ish character players like Gary Oldman and John Malkovich.
In other words, I never once (for a second) "bought" Tom Cruise as a grizzled, burnt-out, one-armed German army officer in the new wartime thriller Valkyrie -- but because he's a movie star who knows how to carry a flick, he still anchors the tale with a strong and crisp screen presence. And while, yeah, it is a little distracting to hear high-ranking German soldiers speaking with American, British and Irish accents, the simple fact is that Valkyrie is a very slick old-school-style adventure movie. In some ways it feels like a perfectly enjoyable mid-'50s war movie that's been re-made with only the finest in modern cinematic technology. The plot is pure potboiler, but the look is grade-A Hollywood.