She doesn't fly. The Force has often been portrayed as a form of telekinesis so she uses the Force to move in zero gravity. That it is being critized shows the imagination failure and nit picking of so many SW 'fans.'
*Shrug* My problems with it were:
1. TFA, and moreso the supplemental material (which Lucasfilm has been emphasizing is now canon since 2014), made it pretty clear that Leia never got beyond the rudiments of Jedi training. This may be less of an issue when seen in conjunction with Rey's ability to do just about anything without any training.
2. It gave me flashbacks to the end of
Star Trek: Nemesis.
I saw the film on Saturday, and it was more or less what I expected based on the review of my go-to reviewer and the spoilers I'd been exposed to--a fun ride and a visual delight, but with overdone humor, conflicting thematics (sacrifice to save lives is good except when it's not?) and highly debatable characterization choices. Then again, I'm not sure I went in with an open mind. I am
heavily invested in the Expanded Universe, and while I was perfectly willing to give the New Canon a chance, I'm just not finding it as satisfying as my curated, selective vision of the EU. There's nothing in the New Canon that's hit the lows of the old EU, to be sure, but I could ignore most of that stuff, and there's nothing in it that matches the stuff I liked the best, either.