Before I say anything else, I should point out that anyone who claims that they can't invert their plane or do a roll in ACAH didn't have the sense to even look at the options menu. Seriously. This option between control styles has been a thing since the PS2 Ace Combat games, and even if it wasn't, why would you not check the options menu?
I actually really like ACAH, but with two major complaints.
What are those complaints?
1. Helicopter missions literally give me a headache. I almost didn't buy the game during the last free weekend because of this.
2. The infamous DFM is required to take down certain enemy aces, and there's no shortage of these aces.
A minor complaint I have is that in the cockpit view, the HUD isn't integrated into the cockpit. I'd be fine with stunting my abilities a bit (as an optional thing of course) to have a slightly more immersive cockpit.
Those two msjor points certainly do damage the game, but it's still an arcade flight game that I find myself coming back to more often than others. It's just a lot of dumb fun. DFM is actually a nice mechanic when it's not shoved down your throat, and being able to get right up into the tail of an opposing fighter as it explodes makes for an interesting change than just seeing a tiny puff of smoke a kilometer or two away.
DFM for the most part is a system about managing your speed to be able to keep on the tail of an opposing fighter while being able to easily lock onto it and/or shoot it down with machine guns. If you get in too close then an enemy can pull off a counter maneuver to get behind you or simply make a hard brake into a direction you're not expecting to escape your sights, but if you're farther away, your acceptable lock-on circle gets smaller, and obviously it's harder to hit with machine guns. It's not quite as "on-rails" as some people would have you believe, but it certainly does assist you quite a bit in maneuvering.
An interesting note relatinmg to DFM is that I find myself actually having to use DFM to perform as well as in other titles. For whatever reason, pinning an enemy with machine guns seems much harder in ACAH than other arcade flight games I've played. I'm not sure if it's the speed of the game, the AI, or the control sensitivity, but there it is. That said, dropping behind an enemy and firing a couple of missiles works just as well as ever... unless it's an enemy ace. Then it doesn't do anything helpful at all.
As much as I like DFM, the game would most certainly be better if it didn't shove it down your throat (I know I made this point already, but it needs to be said again). It takes you on scripted sequences through exploding set pieces, which looks cool, but I'd rather just be able to take down enemies as I like and as fast as I can.
Aside from DFM, ACAH makes good use of visual effects to give it a pretty nice sence of speed not captured in most games. This is actually a large reason that I like the game so much, even thought it's pretty much a purely aesthetic thing. The feeling of speed is just... nice.
Anyway, Ace Combat: Assault Horizon is a fun game. It's not like other games in the genre (or even in the Ace Combat series) due to its controversial DFM system, but that's not such a bad thing.