The apartment is very spacious, the bed was comfortable and the kitchen has all the things you need to cook some simple meals. We stayed on the third floor and the building has no stairs but I guess if you want to stay in the old center of Rome (or Paris, Venice, Florence,... or most of the old places in Europe) that's something you'd need to get used too - so pack light if you could because stairs are narrow and steep..
The staff was very helpful. Communicating with them was so easy. There was some problem with our toaster, emailed them, got replied immediately and a new toaster was brought over on the same day. They also gave us a list of places to eat and shop.
The location is great.Simply Supermarket is 6 minutes away and you could get groceries from them to cook at the apartment. Many bus stations nearby. We walked to most of the main attractions, Campo de Fiori is 5 minutes away, Pantheon and Piazza Navona about 10 minutes. We walked to Coliseum - the Forums, Trevi Fountain & Spanish steps as well which should be easy if you like walking.
Overall there is nothing that we were unhappy with. Although more English speaking TV channels would be great, it is a very strange experience watching Kungfu movie and everyone in there speaks Italian!