I just got it yesterday. It's quite badass, but hard as hell (for me at least... never been good at racing games.)
Keep having a problem with my back tire not having traction coming out of turns, and I haven't pinpointed what it is yet. Not doing anything specific each time to do it, and yet my bike's fishtailin, been pissin me off.
Plus, I'm REALLY bad at holding a turn. Pretty high sensitivity on the lean angles in the game... i'm much better IRL :-P
You are probably running on %100 sim... that is new, and it is hard! Try backing it down a bit (settings on the main menu screen, all the way at the bottom, you can't see it until you scroll down, its below Spectator: No)
Other than that, start out with medium tires. Also, turn powerslide way down, if you are double tapping the gas you are powersliding. Its a good thing to change the controls around so the right trigger is your gas.