Hi Jjay, just some thoughts on 156's, I'm on my second now.
Bad points first.
Still a few reliablity issues, but probably no more than any other Car these days, the most common one's are;
Rear Trailing arm bushes wear out after only about 20000 Miles, this seems to be peculiar to the UK market, probably due to the cambers on our roads. It results in a slightly vague rear end, TBH only keen drivers notice.
Cam Belts and Variators on the Twin Spark's, these need changing at about 40000 Miles, the service intervals are 72K, but Alfa now realise this is too much, and check them at an earlier service charging you for the priveledge.
Occasional Electrical glitches, my JTS had a Plug Coil, then a Lamda sensor fail within a couple of weeks of each other, both were fixed under the Warrenty.
The Odd squeek and groan from the suspension.
Watch the oil consumption, you can't ignore this on most Alfa's or it will bite you hard.
Worst points on the Car itself is a very firm Ride particularly on the Veloce's, but the Body Control is not the best either meaning that on a bumpy road you have to back off more than you would in something like a 3 series, if not you will break something, or bounce off into the ditch.
Good Points then...much more of these, but basically;
They look fantastic, inside and out, they all sound great even the Diesels, they all go great, particularly the 2.4JTD's, V6's and the JTS. The 2.0TS isn't massively fast but has such a wonderfull engine note you can forgive it easily. Seat comfort is pretty good, as is general refinement, Steering and Handling on a smooth road is fantastic, easily more fun than an Audi A4 or VW's etc, you will struggle to find a Saloon Car which is more fun to drive this side of the bigger Engined BMW's.
Best of all they make you FEEL special this goes for all Alfa's, just read some of posts on this site. Most of us are aware that the Car's have drawbacks and aren't perfect, but you can easily forgive them the bad for the good.
Just be warned if you get into Alfa's you will struggle to find any excitement at any other brand. (well any you can afford anyway
If you need any advise on a particular car, just ask, we are a friendly bunch, with a lot of collective experiance.