The main problem with Piccolo Forno is the noise from the harsh acoustics. It is SO LOUD when the place is full! Unpleasant! I was there on a cold Saturday in May at 10pm and the place was packed and very noisy. (Most Pittsburgh restaurants are quiet or even closed by 10!) Don't go there when it's busy if you're looking for a calm ambience. Going at off hours or on a slow weekday or eating at one of their outside tables (if you can get one) would help.
The food: The salads are large, excellent, and beautiful. The pizzas are very good (though I don't think they're as good as when this place was called Regina Margherita - crust not as good?). The last time I had tiramisu here it was very good, though not as good as at Lidia's in the Strip.
Service, during this Saturday 10pm visit, was disappointing: waitress took away my fork with my salad plate and I missed my microsecond window to get her attention.