I'm going to start off by saying that I can be very particular about quality and service. With that said, I don't think that the one and two star reviews are very fair to La Prima Donna.
The cuisine is very good. I lived in Italy for a short time, and I can honestly say that it is very authentic. At one point I told my friend that it felt like I was back in Italy. The food has a very fresh and light flavor throughout all of the dishes. This to me is a sign of artful cooking. I ordered the linguini quattro formaggio with chicken and a glass of Chardonnay. The pasta was perfectly cooked and the cheeses had just enough zing to it. The chardonnay was a great choice and had the perfect lightness to accompany the dish.
My favorite part of the meal was the dessert. If you go to La Prima Donna you MUST order the tiramisu. It was to die for good. My friend had the cannoli which was delicious as well.
In regards to service, I felt that it met my expectations. The staff was very attentive, remembered my name, and anticipated the needs at the table. Yes, a negative experience with a server can tarnish the evening. Sometimes there are a variety of reasons, and it's hard to tell the quality of service with only one visit.
Another bit of advice... this is a great place to go for a romantic evening. The restaurant has these amazing sky lights, a fireplace in the back, candle light, and a fountain. It felt very intimate and comfortable.