Well, I've had my Brera now for a month and had no issues at all.
I know that doesn't help much, but like you I wondered about what I might be getting into. Reading this forum was a great help in drawing up a list of common concerns that I could challenge the dealer on and make sure the car I was looking at didn't have them. Also, I had to bear in mind that people often post about problems, and more rarely about everything going swimmingly - especially in the Technical lounge.
It seems to me that a brand new Alfa is very dependent on the dealer - if a warranty issue arises, there doesn't seem to be much love once they have your cheque. I bought second hand, setting off the necessity for an MOT and no warranty against the depreciation impact and the hope that serious niggles would have been dealt with.
Truly, the joy that driving the car has given me and the fabulous looks far outweigh my worries. I had Saabs previously and they were reliable in the main, and had great mpg, though my last one needed a steering rack replaced at great expense. When I decided to have a Brera, I knew that I was giving up some of that "safety" for beauty and enjoyment and budgeted accordingly.
Every time I find myself looking back longingly rather than going where I'm meant to be, I know I made the right decision.