2.2 and 3.2 petrols are great.
Both have power, but unfortunately drink fuel like its going out of fashion.
3.2 sounds great, though the 2.2 does too under the throttle. You may want to get a remap done on the 2.2 if you go for it as it can be a bit hesitant between 1000-2000 rpm, and the remap also loosens the engine a bit too.
Best performance on the petrols comes after about 20K miles so buying used is a good idea.
On the 159 / Brera there is not much wrong, built like tanks and hold the road brilliantly. Look out for noise from the steering rack as some wear prematurely, and also a creaky windscreen on the 159, it can be annoying.
Go buy one, fall in love and enjoy being an alfa owner.
Alfa Romeo Guilietta QV, white, fast, and lots of fun...