Yeah I got it over Thanksgiving break, and was able to get to level 7 before I came back to school. From what I hear, going higher than level 21 means the grinding begins, plus the fact that you need a level 24 car for a level 23 race. The are parts of the game I like (large number of cars, physics, graphics, karts, what little weather and day/night there is), however most of the game seems really half-assed. Doesn't help the Sony basically forced them to include 3D and Kinect support and probably forced them to get it out the door before Christmas.
I really liked the overall setup of GT4 and wish they could have kept it similar while adding the new features. And yeah it's great having some Ferraris and Lambos, but they barely added any other supercars. No new Astons? No new Bentleys? 1 new Maserati? No new RUFs? Hopefully they can get some patches together for the more glaring flaws.