There is no way to take the copilot's seat, no way to eject from it. The ramp opening and closing sounds cut out too soon. Passenger seats should be accessible from the crew door. The mounting area in the back is too small/too far from the ramp, you have to dance around to find it. The inventory area on the other side is too large, you can almost open it from 5m from the aircraft, from any side. The HMD is done wrong: vertical pitch bars should not disappear when you turn your head, the whole point of having helmet mounted display is to know your plane's orientation when you look away. Also, when you tilt your head (via trackir) hud also tilts, leaving you with incorrect understanding of orientation. Resolution of the HUD is terrible and you can not see anything when facing the dimmest sun.
Probably the most important. The autovectoring does not work. It only makes the vector drop to 0 in any position and at any speed. It also doesn't come back up when the speed/altitude drops. The change to 0 is made instantly, with no increments. When trying to take off horizontally as the plane speeds up the rotors start jittering and going up and down, after reaching certain speed they go down to 0 and hit the ground.
It is also not possible to adjust flaps with autovectoring off - don't know if it's your fault or bohemia's. And the scroll menu is terribly crammed, you can turn off the engine by mistake when trying to adjust the vector. You could do just fine without collision lights and crew door IMO.