Never ventured here for dinner, but I've used Sienna Sulla several times for business lunches. The fact that its a smaller venue, takes reservations, and has a simple menu for quick choices makes this a great joint to have a conversation at (barring the around average noise levels for a lunch rush establishment).
The chicken parm sandwich is great, but definitely a stomach bomb (it'll require coffee afterwards to not need rolled into work afterwards) and the flatbreads a decent as well.
Judging by other's reviews, I wouldn't mind checking out their dinner service, but I doubt I'll get to that soon.