I like that the 135i basically introduced me to a whole new hobby- autocross and track driving. In fact, I just got back from Laguna Seca. This new hobby is probably the first common interest I've ever had with my dad too, which is nice.
Entire set:
http://www.flickr.com/photos/jeremyr...7624792514048/
So that's what I like. I started with a powerful, beautiful machine that just keeps getting quicker and more dedicated as time goes on (new parts, tunes, tires, etc.)