My wife and I really enjoyed this apartment, it was clean, comfortable and spacious (although the showers are very small). It is located centrally and it's very easy to get around the city from here, walking distance to many of the monuments and piazzas. Also surprisingly quiet, even with the Trevi Fountain so close by.
The keys were tricky but once we got the hang of it we had no problem.
We enjoyed our stay very much, however would only recommend this apartment to light travelers who don't mind stairs.