If you've played or read about FlatOut 2 or FlatOut: Ultimate Carnage, you'll know exactly what's in store for you here. There's really nothing new that's been added to the formula. The game is a physics-based racer, which means that practically everything around you is destructible, crashable or what have you. In fact, crashing into things is how you'll earn the all-important boost, and once you're at speed and trading paint with other racers, you'll notice slight hints of Burnout ingrained in its design.
The main FlatOut mode works as your basic career path, Carnage mode (from the 360 title) has been brought over and gives you a medal-based progression option, and there are the requisite stunt events that the series is famous for. WiFi multiplayer is present, but it only supports local play, so you can't hop online. So again, there hasn't really been anything new added to the PSP game, which is somewhat unfortunate, though we suppose additions are being held for FlatOut 3.
So what we're left with is, while old news to anyone who's a fan of the series, still a good deal of fun. The racing is just as chaotic as ever, the driving personalities aspect works (though it could still be better), and the mini-games are incredibly fun.
As mentioned though, there are a couple slight drawbacks to playing the game on the PSP. Firstly, the texture resolution is ghastly in some spots. There's a sign on top of a building in one of the early stages that you can crash through that looks like it uses a 16x16 texture expanded and blurred to fit something larger than your car. Not good at all. Some stuff looks good, while other stuff looks pretty bad. The tradeoffs make sense, as the cars and other things you look at all the time feature better work than the stuff that you don't see too often, but there are spots where something is very, very obvious and its low-res texture work really stands out, like the aforementioned sign, part of the ground, or a wall that you race right alongside.
While the framerate isn't perfect, it's pretty stable, which is rather impressive for the PSP given how much physics work is going on here. However, the collision detection between objects (or specifically, your car and everything else) doesn't seem to have the fidelity of the console releases, which affects handling. Your car is still very much on the loose side, though ultimately controllable, but when you hit or run over objects, your car reacts in unexpected ways sometimes. Crazy, out of left field stuff doesn't happen, but hitting a cardboard box may have a bigger effect on your performance than you expect it to while whipping around a turn.