We loved staying in Maria Cristina's apartment! It's located in the perfect neighborhood- walkable (15 min) to lively Trastevere, and central Rome/sightseeing, but outside the hustle and bustle. Testaccio feels like it's still a traditional Roman neighborhood, with lots of lovely little restaurants and shops, and many families, but without the overwhelming tourist feel. It's our favorite neighborhood in the city.
The apartment itself is quite wonderful. It feels spacious and comfortable, well decorated, and impeccably clean. The A/C in the bedroom and living room were a lifesaver, as we came during the summer heat and cooled off almost immediately. Though it's off a main street, the double paned windows did an excellent job, and we were amazed at how quiet it was. The washer was a huge bonus that we certainly used! We also enjoyed cooking in the kitchen (though there's a plethora of places to eat nearby) and Maria Cristina thoughtfully left us honey, cereal, sparkling water, and Prosecco, in addition to the kitchen essentials. Make sure to use the percolator for morning coffee, it's delicious! We spent some mornings/afternoons just lounging in the apt because it was so comfortable.
There are three little grocery stores less than 5 min away, in addition to the Mercato Testaccio, which we loved and went to a number of times for fruits, veggies, and lunch! (A fantastic fresh salad stall, if you need a quick break from pasta.) We highly recommend grabbing lunch from the Mercato and enjoying it at the piazza, which is just a few steps from the apartment. (The piazza is also great- mostly families and locals, plenty of shady benches, and a happy vibe.)
Maria Christina has a lovely place and was so wonderful from start to finish. We highly recommend this apartment, and we're truly sad we only booked a week!