Just based on brief play time:
I wanted to wait until I finished up MGS3 Subsistence to play this game, but I just couldn't resist trying it out.
All I can say is "WOW." This game is easily as impressive on the PSP as Tekken DR was when it came out. Konami somehow managed to do an amazing job replicating MGS3's graphics on the PSP, with detailed character models and environments (although without jungle), all running at a good, STABLE framerate.
The controls didn't take much getting used to; you can change various aspects of them, but the game basically controls like the online modes in Subsistence. Everything from past MGS games is here, including CQC, first-person aiming/shooting, and of course stealth.
The game is a direct sequel to MGS3, taking place six years later in South America. Apparently time moves forward in this game, so in-game time could end up being several years long before everything is finished.
Cut scenes are no longer in-game, but instead of done in the same visual style as the Metal Gear Solid Digital Graphic Novel, having sequential art with some animation here and there. They look very stylish, and the voice acting (done by the returning cast from MGS3) is superb as usual.
To make the game work a bit better on a portable, everything is broken up into stage based missions, just like in the Metal Gear Ac!d games. You can pick them in different orders, and from what I know, you can keep returning to them in order to recruit more members to your squad. I haven't even gotten to the recruiting part yet, but it sounds really cool, and you can make the game last a LONG time by getting the right members and levelling up their abilities. I've heard that just rushing through the game will result in a completion time of 5-6 hours, but that really isn't the point of the game.
It's also made to replayed. I've seen that starting over a second time will net you more playable characters you can't get the first time around. Also make sure to have saves for MGA1 and 2, and the graphic novel on your memory stick. You can unlock Telico and Venus from the Ac!d games the second time through, and another character (who I don't want to say in case it's a spoiler) from the graphic novel save.
On top of all this, the other "meat" of the game is online. Not only are there online deathmatch modes, where you can choose to pit your squad against others and LOSE those characters should you lose the match, but also an entirely A.I. driven online mode that takes a squad and lets them level up in cyberspace. Using passwords, searching for wi-fi spots, or using the PSP GPS adaptor also gets more characters recruited.
So far, other changes I've noticed from MGS3 are:
-The radar is now based on sound. It lights up in different directions depending on where you are.
-You can only carry four items at one time. Not sure what happens once you have a squad out on the field with you.
-No more hunger/heal injury system. It's back to MGS2 style. I have a feeling the trade off is going to be keeping all your soliders healthy instead.
