Which model to choose? There are lots of comparison topics if you do some searching. My brother has a 2008 and I have a 2011 and I guess I've spent enough time in both to have an opinion. Here are the main differences I notice:
1. 2011 is more comfortable on the freeway and at any speed going over large bumps such as railroad tracks and pot holes. There have been a few times on the freeway in my brother's car where he hit a bump and it felt like his car was going to take flight. My 2011 floats over them. Sometimes the difference is huge!
2. In sport mode, the 2011 steering is more taut and precise.
3. 2011 alcantara seating is a bit more supportive. I actually prefer the leather for maintenance reasons but whatever.
4. 2011+ tachometer with integrated electronic speedometer is an improvement in my opinion. It's easier to monitor speed and rpm.
5. Mechanical rear differential is added but I honestly don't know how it compares to the 2008-2009 model as my brother has never snapped his car into a corner with me sitting shotgun. All the reviews say the newer model can hold a corner better and oversteer is easier to control -- but I wouldn't know personally because there's never any open public roads where I live and it's just too crowded and dangerous to try the limits of this car.
I need to look into tracking my car!