I rearranged my timetable so I could play this today, and I have to say it is fantastic. I love the fact that you can change the configuration of the cars, which means you can make the shittier cars more fun to drive.
As for the tracks, I am disappointed with the Amalfi course (the long one). It is far too fiddly to be any fun.
However, Fujimi Kaido is amazing, what a track! I've just done a few laps of it in a stock M1 and it was fantastic fun. Also got up to 6th on the leaderboard for that track and Class C using the M1, only 3 seconds off 3rd place (admittedly there are only 16 clean laps which may have something to do with it). That was with no aids except clutch, as I can't get on with using the clutch on the remote.