I recently acquired a copy of this. I have not had a chance to play it thoroughly, but I have noticed some people here are eager to get a feel for it so I am posting my first impressions of the game.
First of all, I can confirm that this compilation was for sure done by G1M2 - their logo is the first thing you see when the game boots up. The game comes with a really nice instruction manual with quite a bit of artwork and about 10 pages of some Athena based graphic novel. Lots of information on each game - too bad I can't read it (the section headers are in english but all the paragraphs with information are in japanese).
The game is quite easy to navigate. Most of the commands are labeled in english. There is also a save game feature which I have not tried yet but I think it allows you to save your game at any point and then restore that save whenever you want. The gallery mode has nice artwork as well as the arcade cabinet artwork for each game.
Before getting into the games, I must say that the only one I played in its original arcade form was POW, and even that one I only played a few times. Since I am not familiar with the original games enough to tell if the emulation is spot-on or not. The graphics are excellent - it looks like there is a one-to-one pixel correspondence between the PSP screen and the arcade original when viewed in normal mode which takes up pretty much the whole vertical space of the PSP screen and about half the horizontal space. There is also a stretch mode that takes up more (or perhaps all) of the PSP screen but I have not tried it yet. The sound seems fine.
The emulation quality is decent as far as I can tell, but not perfect. I have not noticed any speedup or slowdown in any of the games. I did notice in POW that every once in a while some of the enemy soldiers would disappear for like 1/10th of a second and then reappear. Also, the game would occasionally pause for a moment to load data from disc (this might not be an issue on the downloaded version). Fortunately these pauses only seem to come at times that don't really interfere with the gameplay - like before a boss fight when there is no one else on the screen or after you get hit (you are already dead but have to wait a split second for the "death animation" to load). Given the sophistication of the PSP I found it surprising that it could not simply load the entire game into RAM and just play it all from there without needing to go back to the disc in the middle of the game. Also I was kind of expecting the emulation to be perfect since the PSP is like 100 times faster than the original hardware. Overall though, I still found the gameplay to be enjoyable. Controls are responsive, and being an old-school gamer, I think the games themselves are pretty cool.
There is one major flaw that I do need to mention. Someone please correct me if I am wrong (since I can't read the instructions), but it appears that there is no way do a two-player game! I saw on the website that they were indicating it was a one-player game but I figured it was an oversight or they were just referring to play on the local PSP. Surely they would allow another PSP to connect via Ad Hoc Mode and become the second player on games like POW and Prehistoric Isle, right? Apparently not. I would probably rarely (if ever) do co-op play since this is an import title, but nonetheless I found this extremely disappointing. On the back of the case there is this japanese text which caught my eye because of the acronym LAN:
このソフトウエアはワイヤレスLAN(アドホックモード)には対応しておりません. また,インターネットを介したオンライングームプレイにも対応しておりません.
which, according to google, translates into:
"This software is a wireless LAN (Ad Hoc mode) is not supported. In addition, over the Internet not support online gameplay. "
What?! Over a year and a half in development and *no* online or local wireless play?!
So it looks like we are stuck staring at the upper right of the screen at 2P with a permanent score of zero and the message "push 2P start" annoyed by the fact that there is no 2P start button (or any other 2P controls). Then to add insult to injury, we are forced to watch the second player as the game runs in demo mode! It's like the PSP is taunting you saying "this game is ready to go in 2-player mode and would be twice as much fun, but too bad you will never get to play it that way because the lazy programmers did not bother to include an interfrace for the second player's controls, so I will just show you how cool it would have been if they had! HmHmHmwaHAHAHAAAA(evil laugh)!" Seriously, from a programming point of view adding 2P controls would have been soooooo easy - just provide a way for the emulator to be aware of them and create an interface wrapper that maps to whatever hardware is to be used for the 2P controls - thats it! Given the ability of the PSP to connect to the internet, other PSPs, and even the PS3 this should have been a no brainer! I mean c'mon! At a minimum all you would really need is to be able to connect to another PSP and use it as a wireless controller for the second player - you would not even need to send any graphics or sound to the other PSP because you could simply connect the PSP running the game to a TV that both players could see and hear. While not ideal, that would have been a piece of cake to implement and at least that would allow two people to play co-op!
They should have taken a lesson from the creators of the rather similar Konami Arcade Classics compilation for the Nintendo DS. In that game, you can easily play co-op on any 2 player game in the collection with anyone who has a DS (even if they don't have copy of the game, I think). And in the Konami compilation you can even make recordings of your own gameplay and send those recordings to other players so you can "show 'em how it's done" so to speak.
This makes me particularly annoyed that they did not make a PS2 version as was originally planned. Hope is not entirely lost, though. Maybe they will still make a version for the Wii or PS3. Also, perhaps they will release some downloadable add-on that will enable 2-player co-op for this game. As I had mentioned earlier, it should be very easy to include such a capability, at least at a minimal level.
Please don't let my long rant about the lack of 2-player support deter you from getting it though. I feel like this compilation could have been better, especially if it had support for 2 players, but I am still glad I got it.
If anyone has any specific questions about this game before deciding whether or not to buy it, don't hesitate to post them or PM me and I will try to answer them for you. Cheers!