Great series! Did it endure beyond the PS1?
I'm always down with more flight combat games. 
Ace Combat had atleast 3 titles for PS2;
Ace Combat 4, Shattered Skies
Ace Combat 5, The Unsung War
Ace Combat 0, The Belkan War
They were released in that order. I didn't play The Belkan War, I bet it was awesome though because Ace Combat 4 was very fun and was A+. Up a notch from PS1. Ace Combat 5 was even better than 4. and there was a flightstick built for that one that connected to PS2 via USB. I regretted not getting the flightstick package because that game in particular ended up being my favorite Ace Combat of the ones that I have played. It was more integrated than previous games and I think had even more licensed aircraft than ever before. I played a demo of another Ace Combat game on somebody's 360 about 10 years ago and it was amazing even if it was just a demo.
There were also the 2 games for PSP;
Ace Combat X
Ace Combat | Joint Assault
Both of these games are great, and I would assume any serious criticism of them would be towards control schemes. Both were excellent games, but maintaining control was extremely difficult. High stress. With the limited and asymmetrical set of controls of the PSP, default game controls are kind of redundant / destined for failure. So in both games the controls were 100% customizable, as if you were calibrating a controller for an emulator. I think I remapped every single button in both games too. I haven't played either in a while, but in order to have L1 and R1 be YAW left and right, I had to completely shakeup the entire control scheme and I think I had to completely dispose of the most superficial command, which was possibly the camera toggle. It's very political and stressful. But once you get past that, these 2 games are very impressive on a small screen.
I just picked up a used PSPGo not too long ago. I am really liking it and am using it as my go-to PSP. There is no UMD drive so I just use it to play eboots of just my top favs. I think I am up to 12 or 13 PSPs now but I still can't find an acceptable metallic green Metal Gear one or an affordable lilac purple Hannah Montana one. There was also a bronze one that is near impossible to locate. I have some strange colored ones that were from the Japan market but the bronze one is extremely evasive.
I think I have accumulated about 5 pounds of expired PSP batteries since 2007. That is from them sitting too long. I even had 4 official Sony XLs that I paid retail costs for each one and they all swelled from sitting too long. I try and keep them all in rotation now and don't let them sit too long without a charge but it gets confusing. Plus the 1000 and 2000/3000 batteries are rated different from one another, and sometimes I'm using a beater that doesn't take a particular battery. The great responsibility of PSP battery management. I wonder if Sony still sell the refurbished XL batteries. Mine lasted about 8-12 consecutive hours with UMD running and casual internetting going, which is a little more than twice a long as the standard battery that came with the units would last. These were almost twice as thick and required a supplied oversized replacement battery cover that could accommodate the size.
I used to rest assured knowing that if the power went out again, I would be good for about 3 consecutive days of pure blackout. Plus I do like taking long train trips and although they have AC outlets on board I like to live the PSP life as a sovereign.
I don't trust third party batteries. I used a fake battery once and that PSP ended up in my dead pile. It was pristine shape with almost no usage, and was my only black 3000, I blame shitty fake Chinese battery. ; D
The stress of battery expiration. You must not neglect the 3.6v 1200mAh. Nothing more annoying than having to play a PSP while it is wired to a wall outlet. LOL. A couple of my PSPs don't even have batteries anymore because they sat too long and ballooned like crazy.
