From memory Shift 1 wasn't quite as bad, but was still a steep learning curve. I couldn't drift that game at all, but that was also before I had access to great resources for tuning tips.
Sure, the handling model is no GT5, but that's just one reason why I like it - It's more challenging, more of the time.
There's a much greater satisfaction from winning in Shift 2 because not only have you tuned the car right, (or chosen the ringer car for that group) out-driven the much better AI, AND you've also overcome the flawed physics to master everything. With GT5, for me at least, it's become a case of sticking the super-sticky tyres on and driving past all the moving obstacles that are the so-called AI. Then simply race off all by yourself for the remainder of the race.
(Of course, you could say "Racing soft tyres don't give realistic levels of grip,,," Well, none of the tyres in GT5 do. If you truly believe some people in the GTP community then Comfort tyres are the only ones that give you real-world grip. Sorry, but every driver on the road would be dead by now, along with all the pedestrians. Besides, when you set out to win a race, you only fit the best. I don't see any Formula 1 cars currently running with a Prius engine and classic cross-ply tyres.)
In my personal opinion GT5 feels like a clinical and cold, Hi-def advertising platform for the car makers, whereas Shift 2 has much more long-term playability, and crucially, challenging fun.
EDIT: Favourite drift circuit is definitely London Millennium. Such a shame it's not scored the same as in Shift 1. I seem to remember you could run around the inner loop all day and it would continue to count the score. Well, I guess I'll just have to put up with a lowly 2200 or so from 2 laps in the E-Type.