Just beaten this, thoughts below:
+Decent graphics especially the sunset/rises
+Physics generally feel OK aside from the odd minor piece of vegetation made of solid granite that takes you from 200-0 instantaneously (like 90% of racing games)
+Good variety of vehicles and I like how the races have a range of restrictions, forcing you to experience a range of motors
+Upgrade mechanic works quite well meaning cars are viable over a range of events
+Great soundtrack and festival vibe
+Driving is generally good fun especially showcase events
+Race length is about right for me (everything under 10mins I think), I quite like these short events compared to GT5 which even putting Endurance to one side has some pretty mammoth ones
-Performance isn't great, it is noticeably jerky compared to PC racers
-Stats are a bit misleading e.g. you can have too vehicles with a 10 in a given stat that perform differently
-Characters have no... character and the trash-talk gets very dull very quickly
-Interface is frustrating at times e.g. when trying to find a certain car from your garage to suit a given event you can only sort by criteria rather than applying filters
-Started to feel a little repetitive towards the end, I don't really have much desire to go back and cleanup the remaining events I haven't won
Overall I enjoyed the game and feel it was worth the £15, feels kinda like TDU.