Contrary to what some reviews have written, I found Tom Cruise excellent, beaming out confidence, authority, insight and integrity into the main character. I can hardly think of a better way to play that role.
I was surprised also to find out that the story was not just about a bomb that did not kill Hitler. The whole Operation Walkyrie was in fact more than that, it also consisted of a whole plan to take over power after Hitler's death. That was not the intention of the Operation as written but that was how it was used. Almost half of the film deals with what happens after the bomb goes off. Eventually it fails because it turns out that Hitler did not die, and was able to win back a few key allegiance that turned the situation against the plotters.
Lastly, I was wondering why people who don't really have the historical background would go and see the film. I was with my Asian girl friend (OK I was not in Belgium) and she understood little to nothing of the film, even as I tried to explain her bits of it. The cultural gap was just way too wide to cross. In this respect, it certainly is not a mass-friendly movie, and it's amazing that the movie had the success it had taken that into account. No doubt, the fact that it's Tom Cruise is for a big part in the attraction the movie has out of the US and Europe. I doubt it would be enough to make it a real success on foreign market, though.
On the whole, great realization and acting, and a very instructive movie from a historical perspective, but it's not going to be a second Top Gun.