Lis Mari's place is great for a single traveler or a couple. It's exactly as described. It's a bit far from the center, but there are many public transit options in very close proximity of the apartment (both busses and a tram), that will take you anywhere in 20-30 minutes. Some reviews mention a neighbor's dog who lives in the back yard and constantly barks -- there is indeed a dog, but I heard him bark only a few times, certainly never all night long. It's definitely not an issue. The water heater is small, as Lis Mari mentiones, so if there are two people you may not be able to both shower without waiting a bit for the water to heat up, but I was alone so it wasn't an issue. The kitchen is stocked with basic things for cooking, there's an iron and a hairdryer, so it's really like you're staying at home.
Lis Mari is also a wonderful person. I had my handbag stolen my last day in Rome, and she came right over to let me into the apartment and also lent me money so that I can eat that day and get home the next day. She has a detailed binder with all sorts of advice on Rome, so even if you come a bit unprepared, you'll be fine, and you can always reach her if you need to. I would not hesitate to go back and stay at her place again. Thanks for everything, Lis Mari!