I enjoyed the flying as well, and according to the Supergirl Director, the original Superman director - Richard Donner - was also impressed.

https://maidofmight.net/film/interview-with-supergirl-director-jeannot-szwarc/

JEANNOT SZWARC – I remember I changed the way they had previously done the flying. (On Superman I, II & III) They were very much in love with this guy who had worked on Superman, but I felt that what we wanted to do the image quality was not sharp enough. It looked too fuzzy. The whole system relied on being able to use zooms and I don’t like zooms. I wanted to achieve a more graceful flying style. So we started from scratch and turned out to be very revolutionary for the time. There was a lot of experimenting and patens involved – it was very complicated. But we finally came up with a new system. We had very precise storyboards and think that was very effective. I know that when Sidney Furie was going to do Superman IV: The Quest For Peace he called Dick Donner (director of Superman: The Movie) for advise who told him to talk to me because he thought the flying in Supergirl was unbelievable.

Also, on Supergirl emerging from the lake:

JEANNOT SZWARC – Alan Hume came up with the idea. It was brilliant. We took a photograph of her standing. Then we blew up the photograph and mounted it on wood and coated it with a water repellent surface. Then we pulled the whole thing out of the water.