I was an Alfa virgin when I bought my GT JTD in June. It is on an 06 plate and is pretty much fully loaded so benefits from heated leather, headlight washers, xenons and the 18" wheels, with the exception of retaining the original (crap) CD player.
I love the way it drives and the way it looks and my friends love it. It is okay around town and in heavy traffic, though the turbo lag and long gear throw can become tiresome. On the motorway however it is a composed and comfortable cruiser with great mid range punch, whilst on the open road it is absolutely fantastic with sublime handling, though the standard brakes are perhaps a little spongy. Fuel economy in all conditions is exceptional.
For the money I don't think there is anything else out there that offers such a great all round package in terms of looks, performance and frugality.
Soon after purchase I had the power increased on mine to around 200bhp which makes it infinitely better to drive - I found the standard diesel output to be a little tame for me. I strongly recommend this as do most owners who have had it done as it makes the car so much more fun and usable. Doing so however will likely reduce the lifespan of certain components, but touch wood I haven't had any problems so far. There are a number of different avenues to go down to achieve this be it remapping, tuning boxes or the somewhat controversial but effective Mangoletsi power modifications.
Mechanically the car hasn't missed a beat really - there was a slight suspension issue but this was fixed under warranty.
However, it is more the durability and build quality that annoys me and makes the car a somewhat bitter sweet ownership proposition. It is as if Alfa just couldn't be bothered to properly test or build the car (I suppose it was only supposed to be a stop-gap before the Brera arrived). This really bugs me as what could have been an 'exceptional' car is left a 'good' car.
In mine the leather drivers seat and steering wheel has worn badly, the heated seats are a little temperamental sometimes only coming through lukewarm, others blasting you with the power of ten suns! The footwell heaters have stopped working, the interior door handles are peeling and badly worn, the exterior door handle sticks, the boot lid used to rattle terrilbly, the doors needed adjusting due to excessive road noise, the electric windows continually play little games (though always eventually close with some encouragement) and the steering wheel stereo control buttons have worn badly.
Perhaps owners of the face lift model can report a better built and finished cabin?
For a three to four year old car that has only covered 36k and that retails out of the box for £20k+ I find this a real let down.
However on the flip side I bought mine from Mangoletsi, a main dealer in Knutsford and despite a bizarre sales experience where I was ready to put down a deposit and yet the salesman didn't return my calls for near a week (!), the afterservice has been absolutely exceptional. I got a years warranty with my car so most things have been fixed either on warranty or out of goodwill. The staff are all very friendly, welcoming and polite. I always get a GT as a courtesy car when my car has been in and they are always happy to let me test drive other models in the range. Also the coffee is bloody amazing!
Because of the excellent dealer support I have had I would still rate my overall experience so far a positive one, despite the numerous irritating niggles. I suspect if I had bought my car private however I would be very annoyed and would have clocked up some considerable bills just having minor faults put right.
I hope that has given you some honest, objective and thought provoking feedback. Keep us informed and good luck with your search!
Despite all the irritating niggles I would still recommend it is a very good car.