You can change the color of your car, alter some of the exterior parts (hood, spoiler, front and rear air dams), and sticker the hell out of the cars. It also features some tracks styled around the Initial D anime series, and these are a blast. But, the one feature that is a stand-out, and keeps me playing, are the items and posters you win for completing races. You can then place them in your garage, wherever you like, and it's wickedly addictive. I can spend an hour just designing the layout of my garage, calculating what's the most efficient organization. It's like a barbie doll for guys, and makes me long for a garage of my own.
I've never understood people who take a garage and turn it into just another room of the house, or use it simply to store things. It's a holy place, a shrine to tools and automobiles, a refuge for your vehicles, and should be a vital part of anyone's love affair with things that go fast.
If you've got a great garage, send in your photos and I'll post them here for all the world to see.