Stayed in studio 15 in Feb 2014 and studio 10 in March 2014. Studio 15 is tiny and on the highest floor but studio 10 was great! Place was really clean, and the wine and beverages in the fridge were a great touch! If not mistaken, studio 10 had higher ceiling and 2 windows. A lot more floor space, so if you are staying longer than a couple of days, I would recommend 10 over 15.
Check in and check out was a breeze.
Location was a great for us since we walked everywhere. It is in a quiet residential neighbourhood and we felt safe even if it was late at night.
Alessandro helped answer all the questions that I had (and I had a lot since it was my first time booking with airbnb). There was only one occasion that he forgot to respond back to me and went missing for a week, but other than that, he's always quick to respond, usually within hours.