Although the Bloomfield neighborhood is said to be the Litty Italy of the city (don't miss the homemade ravioli for sale at Groceria Italiana), I don't think it contains any great Italian restaurants. Some say D'Amico's is great - I disagree but I decided so long ago about the place that I haven't gone in years. Alexander's and Lombardozzi's and even Mariani's Pleasure Bar are good, but not great.
Piccolo Piccolo downtown I'd recommend. Alla Famiglia in Allentown is tasty, but somewhat overpriced.
Really I'd say the non-local Lidia's (in the Strip District) is my favorite, with Dish (South Side) and Cucina Flegrea (Squirrel Hill) and Vivo (in Bellevue) all tied for segundo. Tell me - where's the great place am I missing?