Apartment is perfectly located in the center of Rome. You can actually pop into the Pantheon whenever you feel like it. From here, one can walk most anywhere in no more than an hour.
Yes there are stairs. If this is a problem, you should stay elsewhere. However, we didn't have any issues.
The apartment is fairly comfortable and we had no issue with the bed or heating/cooling, which worked well. Two bathrooms are definitely a positive, as is the washing machine.
Stefano and Valerie were very hospitable. Valerie took the time to give us many tips. Also they provided coffee and cakes; nice touches indeed.
Overall I totally recommend this apartment for anyone taking in the sights if Rome.