Actually, the "Over paid, over sexed, and over here" phrase does date back to WWII and the U.S. soldiers being stationed in Britain.
As for "Valkyrie", I was very pleased. For a Hollywood film, it was very historically accurate telling of the July 20th plot. As far as events goes, they followed history almost exactly. About the only glaring differences was that Stauffenberg was drawn into the plot by his Uncle, and one of the conspirators, Goerdeler, was made more antagonistic in the film than he was in real life. As far as performances go, Tom Cruise (who does actually look very similar to Stauffenberg) held up his end against an absolutely stellar supporting cast. And even though you know the outcome, Singer manages to keep you on the edge of your seat.
About the only complaint I had about the film is that it did not really examine the conspirator's motivations in depth.
But most of the complaints I have heard leveled at the film are: "Tom Cruise is a crazy Scientologist" and "There all speaking English! How dare Hollywood make a film about Germans in which they all speak English!" Which if people are reduced to that level of nitpicking, it's a pretty damn good film.