Rome is rather cold in December, so it's a great feature that this apartment has a heating system. It helped a lot.
Apartment is located right in the middle of Trastevere, so you're in the middle of the action and all the attractions are easy to reach, that is a huge plus. Also, shops, farmacy, etc
I would not recommend trying to go to sleep before midnight (we tried to before flight), as you won't be able to with the noise coming from the street or the noise from the restaurant kitchen. This inconvenienced us a lot, we tried switching rooms (bedroom to living room), but we still could not hide from the noise. So prepare to party until late or bring earplugs :)