What impressed me was that they managed to include pretty much all the major plot bits and add a good bit more backstory. It was nice to finally get some more info and characterization for Linith, for example, who seemed to show up out of nowhere in Fate's dream at the end of A's (yes, I've heard she's introduced in the Sound Stages; that doesn't do me a lot of good).
I do suggest, if you haven't already, that you track down and read the manga for the movie. Though it splits off into AU, it still includes even more backstory, including explaining those flashes from Nanoha's memories we briefly see when she's deciding what to talk to Fate about, among other things.
I do wonder how they're going to handle A's though; canonically, the movie exists within the Nanoha universe, but as I understand Admiral Graham's actions, which kinda drive a good chunk of the plot, aren't exactly supposed to be public knowledge. Guess we'll just have to wait and see.]]>