I winced at the P-51 backflip but honestly didn't notice anything goofy about the formation flying - although I hardly had time to see much since the scenes change so rapidly.
I'm prepared for a certain amount of Hollywood treatment, and I'll overlook inaccuracies like the wrong tail code on the B17s, etc - because it is SO SO SO much better than seeing a C130 sub for a Japanese patrol plane in the 70s-era "Midway" movie, where Hellcats served as Wildcats, or the corny model-plane-on-wires Japanese fighters of Duke Wayne's 1942 "Flying Tigers" film. It looks like they spend a lot of time in P-40s, too, which is fantastic.
I hope it has such success that it generates interest for several more WWII air combat films (would love a "Band of Brothers-style series on the Flying Tigers). I'll probably read up on the Tuskegee Airmen, too. I figure there's a lot I don't know about them.