As a lifelong Pittsburgher, I've been to Tambellini's enough times over the years -- and I think it's still open simply because of it's location practically next door to the Benedum, and patrons who go there aren't the regular theater-goers. I was invited to go with friends, who were old enough to remember when it was probably good.
The prices are *outrageously* high for the quality of the food and portions. I had the Chicken Marsala, which was alright, but something I normally eat served out of a chafing dish at a funeral buffet. This was comparable to a catered version and the restaurant itself deserves a funeral... It's outdated and just a factory for getting people in and out and on time to the cultural events they're going to.
The waitress was nice enough, seemed a bit embarrassed to respond 'no' when I asked if certain menu items were fresh. On the other hand, she disappeared quite a bit and didn't ask if we wanted any desserts -- which we probably would've if we'd been asked.
Even though Downtown after business hours isn't the most exciting place to eat, there are other places I'll insist on going instead of back to Tambellini's.