I bought my 1.8 5 door brand new a year past july.
You get a lot of car for your money, but depreciation is horrendous. Great if you are looking for a used one.

(I'm open to offers).
Performance - well, it's all down to opinion, what are you used to and what are you comparing it to? 133 bhp is around 2.o litre focus power, but in a heavier car. The focus handles much better, even the last one I drove, which was the 90bhp Tdcl. Having said that, I've done 20,000 very comfortable miles, been to France twice with 2 kids and the boot chocka.
I agree the brakes are quality. You'll have to drive ityourself to decide if the performance and handling are what you are after, but for me economy comes it to it, and it's a great balance. I wouldn't trade less economy for more performance. I get 36 mpg travelling to work, a 20 mile journey on fast A roads, and I usually hoof it a bit but never take it into the red.
Build quality: awful, but you'll live with it.
Dealers: a joke.
If there was a way of knowing for sure that you haven't got the suspension problems that cause tyre wear (and an inability to get anywhere in the snow), then you'd probably be happy with a Stilo 1.8. Sadly, there is no way of knowing until your tyres wear, and you've got very little chance of getting the problem fixed by Fiat.
My judgement may be clouded by the tyre/suspension problem, but due to dealer incompetance, and the fact that I was offered nothing towards new tyres, I'll never buy another Fiat.