Not out until tomorrow (13/12) but I do agree the franchise is starting to get stale. You are technically just playing GT3 over again but with much pretty graphics, maybe some extra courses and of course new cars.
They REALLY need to impliment realtime dynamic weather/time of day and of course, damage. I mean, they pulled off dynamic weather and TOD on the freaking Dreamcast with Metropolis Street Racer (the very first PGR if you will) and it looked pretty cool (I loved how the game used the system clock to set the time of day on tracks etc, and used time zones to compensate) so if you only ever played the game at night you always raced at night. It was very cool and added alot of detail, as the game always looked different every hour.