Seems like the release video shows the fly spell (timestamp 1:01). If that's so, fly looks a lot more like Feather Fall than full-on angel wings.
It will probably work like in D:OS2 - you hover over the ground not interacting with surfaces, and you will get an extended “jump”.
Personally, I don’t mind it. While it doesn’t quite sell the fantasy of flying, it also ticks off most boxes I would want from “fly”. That is definitely one of those things I am more then willing to let slide.
The only problem is when it comes to cross vertical gap.
I already had the issue with the flying pet, unable to go from the ground to the upper part of the door at the githyanky encounter.
The game didn't allow it because I was too close so the arc went into the wall.
I think that the flying spell will be more situationnal than it should with the map design and the jump spell will probably often be more optimized. Not really an issue to me even if it's sad.