Only gotten past the prologue / first 'boss' on the tallest building, still playing through, but some initial thoughts:
Holy crap the amount of work that must have gone into this-
Flying is fun once you figure out how to get off the ground (w + shift + space + mouse up so you don't immediately land) but walking/running with tank controls is misery. Trying to use the the quantum teleport gates when its a struggle to walk through a small gap accurately is no fun. If input had been relative to the camera this wouldn't be an issue.
In general there's a lack of cohesion to the control scheme: flying takes mouse input + spacebar and moves in the direction of the camera, walking is tank controls with WASD. Mouse sensitivity in flight is excellent but too much when flying stationary; I found I had to pretty much fly up into an enemy's face to aim worth a damn.
Combat in general feels... off? Flight is unquestionably the best part of this game, so having to stop to shoot feels strange. Given enemies completely fail to lead their shots stopping is also the only way they can hit you; combine that with the aiming issues mentioned earlier means combat pretty much boils down to 'fly into enemies face and trade hp until they die'. Your health regenerates, their's doesn't, ergo.