I own a bog standard 150bhp clatterbox GT.
It feels averagely quick, though sometimes I think I don't have anywhere near 150bhp. The ride is harsh at best. It bumps and rattles a bit, though in mine the cabin is well screwed together and it seems to be the suspension that suffers noises and all but the anti-roll bar bushes have been changed.
The seats are the best I've ever sat in, ever (did I say ever? well they are
). Having the radio on keeps the little bit of clatter (at idle) and clunky suspension quiet, so that's what I do. The 1.9 diesel has potential but sounds absolutely sheite.
The GT looks very nice, even in black (buy red or that met blue though).
I've been a passenger in a Brera 2.4. It felt fast, very fast. It sounded lovely for smoker, I think the 5-pot is a beaut. This one was also red. It was comfortable and I don't care what the rear seats are like because I never use them. Two of our three cars are two seaters and even the GT is not large in the rear!
Again it felt to me much, much faster than the GT. I will say though as a passenger you feel how quick the car is compared to the driver.
I'd buy a Brera, although if I'm honest a 939 Spider