Initial D on the PSP was fun, and... A bit disappointing. Bunta mode makes up for the disappointing difficulty by giving you an opponent who grows with you. For 15 levels, then he starts to beat the shit out of you.
Anyways, the game has a surprising amount of thought put into realism (as expected of Initial D, of course). Ditches on multiple, but not all courses, allow for high-speed cornering, provided you can control the car enough to make sure it doesn't hit the railing a millimeter beyond. Each course has its own difficulty step, each one teaching you something new about how to drive your car. Each course has a "line" this is both best for what you're driving and is logically sound.
You can beat the game with any car, without any upgrades. As Initial D has always emphasized, the car is not as important as the driver who makes it run. Be forewarned, however, that any car without upgrades will be extremely hard to win with in the later stages, especially on Bunta mode. Fucking Bunta mode.
Now, here is the crux of the problem with this game- Collisions. Collisions in this game are crushing when it comes to your chances of victory on normal/hard mode, but really, it's just you slowing down at a steady rate or not being able to accelerate for a while. On top of this, car collisions are literally not programmed into the game; If you were to drive your car up against your opponent's, your car will spaz the fuck out and go all over the place. Sometimes, I find myself jumping in front of the enemy car by simply crashing into it, and it's in a way that I, for a moment, am unable to comprehend where exactly I am. Loss of concentration can lead to the end of a deathmatch, and the existence of this glitch-like error does not majorly affect the AI in any way.
Let's talk about AI a bit. The AI in this game is by no means genius, but MY GOD WAS IT MADE BY A GENIUS. When racing against side-characters like Itsuki and Iketani, I can feel their archetypes. That's right, I literally feel them. I remember thinking "Oh, this guy isn't good at all, just has a nice car", or "Her driving is so gentle...". On top of this, and this is especially evident in 15-star Bunta mode, they use the difficulty level to force you to find the best line for you, and ultimately make you unbeatable. The problem? Collisions can sometimes actually help you, like how I won every race on Akagi by crashing into the first few hairpins and 4th gear full speed.
So my verdict? 7/10.
The game is by no means beatable by a fairweather ragequitter. It takes commitment, focus, and smarts. Most importantly, you have to learn to manage your upgrades. Upgrades are not bought with money or any sort of placeholder for money. You get cards after a battle, some of which are useless, one that unlocks Bunta mode when you view it in the gallery, and a lot of car part cards. You upgrade by using up these cards... forever. They're potentially infinite, but you'll never be able to fully grasp their power until you push both yourself and your car to the limit- and lose.
The game is for racing beginners (meaning all of you guys who think you're experts at EA racing games). If you want real challenge, try the arcade game.