There's a lot about this I dig - and I say that as a big fan of the IP. ScarJo seems like she'll do just fine - maybe a bit one-note in her broodiness (as she usually is), but admittedly that's not exactly off-key for the character. Also, minor note: they should probably cut that de-cloaking shot from the final film. The contrast between Major and her background reminds me of the live action Speed Racer flick, but in a bad, unintentional sort of way.
Edit:
Visually, it might have been a good idea to darken the flesh-toned suit. I get that it's closer to the source material this way, but something about the color bumps in the translation from anime to live action.