Yes, the game is unfinished but you can still have a tremendous amount of fun with it and you know that it is being worked on. Definitely worth buying, especially when discounted!
I was chasing down some 109s last night in a custom single player FMB mission (
checking the damage modelling and testing their weak spots) when one of the AI 109s just in front of me cut quickly throttle and climbed, flipped over into the start of a split S and nailed me on the way down. As soon as I saw him start to climb I knew he had me but not enough time to do anything about it. Not perfect but you can have some good fun anyway!