First of all, I have to say that the graphics in Dissidia is on par with some of the best looking PS2 games. If you've played Crisis Core on the PSP and you think that was beautiful, you're in for a pleasant surprise upon playing Dissidia.
Dissidia features 20+ characters, 10 heroes and 10 villains from FFI to FFX (expect the familiar faces like Cloud, Squall…) plus 2 secret characters. The battle system is somewhat similar to the battle system in Kingdom Hearts 2. It's like a mix of a fighting game and an RPG. You get two types of points, Health Points (HP) and Brave Points (BP), HP pretty much explains itself; as for BP, that's your ‘attack strength’, in another word, you reduce the opponent HP using your own BP. The higher the level of your characters, the higher HP and BP they will have (you can also equip items and accessories to raise these two points), this means that you will be disadvantaged against someone with higher level characters and vice versa.
The stages are pretty big, most of them have their own stage specific ‘actions’, which are pretty cool (running on walls and riding on streams of light are my favourites). You start off with 11 stages, after clearing a few story modes, you can then unlock a new ‘version’ of your stages. So there are 20+ stages in total.
One of the main modes of Dissidia is Story Mode, you start off with 10 story modes and unlock a few more upon completing the first 10. Since it's an RPG, and it's Final Fantasy, the story is cliche, very cliche. All 10 heroes must gather 10 crystals in order to save the world from Chaos, while each of them must confront their own nemesis and insecurities in order to get their hands on the crystal. Unless you've played first 10 Final Fantasy games, then you will be at loss when playing a story mode of a character from a FF game that you have not played before. For the FF games that you've played, you'll probably feel very nostalgic playing those characters' story. Dissidia really does make you want to go back and play all the old FF again.
There are 20+ background tracks in Dissidia (2 from each FF game). You have the ability of selecting which one before a match. Ever want to relive that epic battle between Cloud vs Sephiroth? Simply choose Cloud and Sephiroth (did I ever mention that you have to unlock the villains by purchasing them using points, I will go more into that later). Anyway, after choosing Cloud and Sephy, you can then choose the ‘life stream’ stage from the stage selection, then select “One Winged Angel” before the battle start, awesome isn't it?
Beside Story mode, there's Quick Battle, Network (you can actually play this game online), PP Catalogue (this is where you purchase new characters, costumes, EXP boost, profile icons etc…), Museum (which has to be unlocked) and Option. It doesn't seem like much but there are a lot, and I do mean a lot, of extras that will keep you playing. For example, there are countless of weapons and accessories, new skills for each character, collect all the summons (there are 50 if I remember correctly), collect all the profile icons… Expect to sacrifice at least 100 hours of your life if you want to unlock everything in this game.
Last but not least, I want to talk about one of the coolest feature of this game. A feature that is exclusive to this game only. Ever wanted to make your own Advent Children style fight scene? You can with Replay Editor. After any fight against the CPU or another player. You have the option of saving a replay of that match. Then you can go to Replay Editor in Museum mode, fiddle around with the camera angles and make it into a masterpiece. That's not all, after you've finished touching up your work of art, you can then record and encode the replay into a .mpg movie file (watchable on the PSP and PC) via an option in Replay Editor. That's right, not only you can save and edit, but also publish your own fight scene with this game.
Dissidia was tailored made especially for the Final Fantasy fans. So if you're one of those, make sure you snatch up a copy for your PSP. If you don't have a PSP, buy one so you won't miss out on the awesomeness of this game. I wouldn't really recommend this game to the none Final Fantasy gamers, but if you're looking for a top-notch game for the PSP, then look no further and get Dissidia!