Scratch that about the music, I'm talking out of my arse. The menu music, although similar, is diferent (I would say its more techno, but I don't listen to techno, so I wouldn't really know). The in game music is much the same as some of the music in previous games (in the demo it was an orchestral piece, reminded my a bit of AC5 (zero still has the best soundtrack though)).
Anyway, I've just played the demo again, by christ there are a lot of planes to shoot down, I spent a good 15 minutes just dog fighting, also the AI seems much smarter now, in previous games the enemies would put in a couple of turns and then just fly straight and level, in the demo as soon as you get relatively close and start targetting them, they start putting in a lot more turns (not wild turns, just very big and long arcs), making it a lot harder to hit them with missiles.
Speaking of missiles, one gripe I have is with targetting, in previous games when you achieved a lock on, you would get a red diamond in the targeting box, in the demo the box just goes red, making it hard to tell when you have a lock on.
Machine guns are good fun though, this time it doesn't take many bullets to destroy an aircraft, the down side is that is slightly harder to target than in previous games, but its still good fun, as ever it feels really good when you take out an enemy with just guns. There appears to be a minor bug in the demo (at least i assume its a bug), occasionally when dog fighting, if you are putting in a hard turn in really close combat, sometimes the gunsight appears to fall off the screen, sometimes even up, which is wrong since it implies that the bullets are going to land somewhere above your plane (the gunsight is calibrated to the range to your target, it shows you where your rounds will land at that range).