Maybe I shouldn't write a review until I've been to all 3 (?) floors of Sienna Mercato, but - I recently ate at the first floor of this place, which specializes in meatballs. I don't really get the appeal, I suppose.
The place was very crowded and loud. The food is mediocre. (I could direct you to plenty of divey Pittsburgh bars with better food), and the service is just...okay.
I tried a couple versions of their meatballs as well as I believe their fried pickles. Everything is greasy, tasteless, and pretty much boring. Perhaps their other floors are better, but I would not recommend the "meatball floor." Good beer selection and probably ok for a quick bite during happy hour time, but that's about it.