We went with a group of 8 (very large for the locale). We did have to wait about a half hour for our 8PM seating (they do 2 per night), but the staff opened our wine and we took advantage of the outdoor seating area. This was through no fault of the restaurant, there was just a group who was taking their time closing out their meal (plus, our group had to have a table moved to accommodate).
The grilled scallies were the best I've ever had. Hands down. I love quality scallops and these were top notch. Perfectly cooked, perfect temp, just perfect. The cream sauce was incredible. The meatball appetizer (weren't listed, have to ask for what's available) were as good, if not better, than my grandmothers. The lamb lollies were perfection. The Duroc chop, perfect. Everything our table ordered (and we shared), was perfect.
I've eaten all around Pittsburgh at some quality establishments, but Wild Rosemary may be my favorite. Gloria, the head chef, came out and chatted with us for a bit, too. She's awesome. The staff was super accommodating as well. You can tell these folks take pride in their restaurant and the food they serve.
Do yourself a favor and book. It's well worth it.