The F30 is about the same weight as the e90 but with more structural rigidity and a better drag coefficient. Despite the fact it's a couple inches longer, it rides phenomenally well, and the steering isn't vague by a long shot (just not quite as good at transmitting road feel as an E90's).
I don't like how the f30 looks except in m-sport form, which I think is brilliant.
That being said, I'll stick with my e90 as it is for a good while. Depending on what the new M3 is like, I may move to that as my next car in a few years.
2011 E90 / Premium Package / Stage 2 PPK / Performance Suspension