The story, I really disliked it at first, then it grew on me. I still skip most of the cutscenes because those tend to overstay their welcome, and the game's over-reliance on Nostalgia gets on my nerve sometimes (Kestrel 2, really? Can't you do anything new?).
I also don't get how the entirety of the USEA continent is held by Erusea's kingdom, since that was the main plot of Ace combat 4, at that point it looks odd that Osea and ISAF aren't allies. And the usual "IT WAS THE BELKANS" twist felt so shoehorned that it was a great comedic relief. Also, the devs really loved throwing gimmicks after gimmicks only to forget about those gimmicks the very next mission. This may give someone a reason to favour a mission over another, but I'd say that going from Dogfight to Sneaking to Precision Bombing to Hide and Seek all in the span of about 4 missions get boring really fast, it feels like they couldn't keep interest for more than 4 seconds. The best missions, in my opinion, were the closest to vanilla ace combat, Missions 8 and 11, where you're sent to demolish some sap's base. Mission 15 ending's new gimmick gets dropped by Mission 18, that's annoying. They had no consistency, it felt like they had to show all the new gimmicks they came out with during all these years since ACAH nearly killed the franchise. For some reason, half these missions are remakes from the PS2 (and even some AC2) games, while it can be nice if these was a "nostalgic mission pack", it gets boring when basically the whole thing of this game is "remember this? feel old yet?"
It's not that mission list must be as big as AC5, which had around 30 missions, although in most of them were you waiting for something to happen, but it feels like that Project Aces tried to recreate what made Ace Combat 5 at the time so "beloved" by the fans but understanding the wrong lesson from that game. We don't want to wait around for a new set of targets to pop up because you're busy giving me exposition for a game whose story isn't relevant. It's an arcade flying game, all we want to do is blow up shit and look cool while doing it.
About the introduced planes: the bad side is that most of those planes are paid, and what I still can't understand is why the final boss's plane isn't an unlockable. You're telling me that the X-02 has become the new super plane after all these years? Why not give me a prop plane while you're at it, you did it in Infinity, which had so much more than this game, when it comes to details and gameplay things, such as explosion hurting you if you were too close.
And I won't have any of those "entitlement" bs, you know it's a bad faith argument.