Well, I have to tell you, I am so in love with this franchise now it isn't even funny. I've been playing the living crap out of Metal Gear Acid, and I'm so beyond impressed. It's just so freaking fun! I don't know that I can unequivocally say that I like it better than straight-up MGS gameplay, but it's definitely a tie at least. Whereas in MGS you get the satisfaction inherent to swiftly maneuvering and getting the job done with a sense of fluidity and even style if you pull it off right, with Acid you get the satisfaction of truly watching a well-planned course of action take shape and bear fruit. And getting beaten back is much more interesting in Acid because things don't just fall apart in this rapid chain of death. I mean, that can happen, but it's all so much slower. You get to watch as your plan fails, and watch the little avenues come and go that could either save you or make things worse. It's incredibly satisfying, and the card battle stuff, which I normally don't care for all that much, just works beautifully. There's this great sense of randomness to everything that keeps you tense and sometimes makes you move really slow while you wait for the right moment, but it also lets you move around within this framework to try and get the best out of what you've got and work things to your advantage. I just can't say enough for Metal Gear Acid right now. If you have a PSP, love Metal Gear, and love strategic stuff, you have to try this. It's amazingly fun. The story isn't bad, either. It's sort of... well, really bizarre right now, but it's entertaining. Not up to snuff production-wise, and some of the dialogue is a bit odd, but I'm still rather curious as to what's going to happen, and it's got some nice artwork and music to back it up. The gameplay is definitely the star of the show, but I suspect the story will get more interesting as it goes.
So... yeah. Go play it if you have the opportunity.