I've been waiting forever to get accepted on tfs and say my two cents on this thread!
So: I really, really don't like italian street style. More: I think, for the 80-90% of it, it's truly hideous.
I live in Rome. And it's just... so... boring. For the most part. Girls can't really dress creatively. It's all black, little fake black leather purses, pointy shoes. This is the most part. Then, there is the people who consider themselves fashionistas and so cool.
They are just so over the top. Too much over the top. Big sunglasses who scream "hey I cost 300 euros". Big logos. Ripped jeans. Chains. Jeans tucked into sneakers (I'm not kidding). It's even a little bit gangsta or ghetto.
There are only a few people who I respect and admire in terms of everyday style. But nothing compared to London, Berlin. Even the shops are quite boring if you are looking for something else.
This regarding normal shops, obviously. If you're looking for something chic and expensive there are a lot of great shops here. From the big names like Vuitton to the fantastic Max Mara/Max&co.
Overall, I think that street fashion in Italy takes very little from international trends and catwalk trends.
Anyway, the situation is a little bit better in Milan. Maybe because there is h&m there to bring something new. I don't know.