I profoundly disagree with the earlier ratings for this hotel. It may be possible that two different hotels exist in Rome with the same name. The Hotel La Pergola that I stayed in was nice (address: Via Dei Prati Fiscali 55, Roma 00141, Italy, phone #+39 06 810 7250, ---).
The staff was friendly, helpful, and certainly went out of their way to accommodate our large tour group. One of the hotel managers, Sergio, was especially helpful, and made our stay pleasant.
The hotel is located next to a grocery store and a Mc Donald's (aka American embassy). It was a short, safe walk and several of our tour members visited one or both locations. The outside of the hotel is fine. There is a very nice courtyard in an "L" shape and many in my group really enjoyed sitting there.
I found the rooms adequate. My only complaint is that the walls were thin - I could hear my neighbors in the next room talking (glad I brought my earplugs). Otherwise, the room was clean and comfortable, with no odors as described in previous ratings. I had the occasion to enter several of the hotel's rooms since I was a chaperone on our tour group, and I also found the same clean, odor free conditions in those rooms as well (of course it was clean before the kids opened their suitcases!).
The hotel arrangements were made for my group by EF Tours. I do not know what the room cost, but I expect that it was a reasonable value.