Went to Prezzo for a friends birthday and it was fairly nice. So much choice for pasta, slightly too much in my opinion. A lot of the dishes seem to be very similar on changing a couple of ingreidents. This makes choosing a bit more difficult.
The pasta dishes were done (or finished at least) in a pizza oven for a nice authentic feel. The food was OK, I wasn't blown away by it, but it was decent value.
The service wasn't the most attentive. When they grated the extra cheese on my friends pasta, she wasn't really paying attention as she was talking and was left with a massive pile of cheese to fight through (common sense would surely mean the waitress would ask "IS THAT ENOUGH"?). When it came to my cheese, she didn't peel the plastic back far enough and I ended up with a couple of pieces of grated plastic wrapper on my plate.
If you're after decent Italian in Oxford, head to Jamie's. I'd say even Bella Italia or Ask would be a better choice.