Well, it's on PS2, so the aliasing is nonexistent, but I actually think it looks pretty damn good. Only weird stuff I've seen is some of the car dashes are out of focus and look like 8 bit Nintendo graphics, but you've got to make changes somewhere to let it run on a PS2.
Overall, the look is a hair more "arcadey", brighter and slightly less detailed in-game than GT4, but it's about comparable. The damage modeling is pretty slick, and the collision models for all the different types of cars (Formula fords, 30's Mercedes, monster trucks, Supertrucks, etc) are pretty dialed; when running the open wheel cars, you get guys coming up and putting wheels into your bodywork, then catapulting over when their wheels hit yours as you'd expect to see in real life, instead of a rectangle of space that envelops the car for impact modeling. In supertrucks, while watching a replay, I saw a wheel that had come loose from another truck bounce up and into the front-center of the driver's door, and it buckled the door at that point instead of jsut a generic "door
erfect - door:damaged - door:gone" that I'm used to seeing.