I am really an Ace Combat Fan, but this incarantion is the worst of the Series. For the first time it is set in the Real World, and instead a cool Story with characters, developement and Drama we get an stupid rubbish about PMC, fake Terrorism to sell insurances. Neither interesting, nor well told.
That alone would not be a knockout, but also the gameplay and Mission Design itself is worse then every incarnation before, even Skies of Deception. Most times you fly just arround and show a few planes ground targets and bore yourself to the end of the mission (difficulty has no real impact, as it mainly affects your ammo and how much hits you take, but nothing else).
Nearly no combat chatter, no scripted events, nothing ... from time to time a boss enemy will pop up, which sadly lacks the effects and scope of the ones from before. Just shoot the Targets and that was it. No special tactics needed.
After 20 missions (5 hours) the game is over, but when you've purchased the wrong planes you can't beat the final boss, as you can't hit him in the last form with everything below an F22, and grind through old missions to get enough money (add an other 5 hours - hours which are a boring grind and no fun)... the good difficulty curve and fair and rewarding mission design was something that made every previos Ace Combat game special - but this game, and especially the last mission is the exact opposite of what an Ace Combat should be. Unfair, not hints, no feedback, no explanation, only frustration until you have the right plane and can see the ending.
After all what remains is a nice looking, but boring to average Flight Action game, with an frustrating last mission. I suggest to avoid it, and better play the previous games (may it be 4-Zero on the PSP, Skies of Liberation on the Xbox360 or Skies of Deception on the PSP) which are all much better, it be in terms of gameplay, story and mission design.
Lets hope they don't mess up Assault Horrizon the same way, but when looking at the new game elements (Quicktime events, horrible action camera ingame, railshooter flying thought skyscrapers) I fear the worst.