The appartement is worth the price because Rome is a very expensive place, but not more. It should be mentionned that this is a basement flat (ie. with one small window, and very, very humid). Aircon is there, but really noisy (hard to sleep with !)
Many positive aspects though, including flat equipment (everything you need for cooking and breakfast), perfect location for a weekend (close to tramway lines 3 and 8, 10min to historic center), and above all Monica's help, flexibility, hosting and kindness !
Globally I would recommend this appartement, but for a weekend stay only. And don't go there if you're claustrophobic ;)