My only knock on Trevi is the noise. Between the fountain and all of the people surrounding you inside the mall (because let's face it, most of this restaurant is a "patio" inside the Forum Shops at Caesar's) it's hard to have a conversation and you're all packed together at small tables.
However, we had great service from the moment we stepped to the hostess stand until we left. We all loved the food and wine, and after awhile, you kind of forgot that you were eating in the middle of a mall.
Prices are high. This is Caesar's, so don't expect Olive Garden prices. The quality of the food is in line with the price. We'll be back on our next trip.