Alessandro's place is in a fantastic location. We didn't use public transport for our whole stay and all the sites are walkable (if you don't mind racking up a few steps!)
Trastevere is a fantastic area and I'd definitely recommend checking out the suggested places to eat and drink on the fridge.
The apartment is very quirky and stylish - the loft bed caused a couple of head bumps but it's very spacious overall. Spotlessly clean and very comfortable!