We had a great time in Rome thanks to Simon's flat. The flat is close to the metro station, the ticket to Rome is only €1.5.
There is a public, free car park under the house. It's hard to find a spot, but if you're lucky, you can park there without restrictions. Our car was never touched or scratched. The neighbourhood is very peaceful, and it's not scary to go home after 22:00.
Of the minuses: it is impossible to have in hands a shower-head, it was hard for me to take shower. The water pours down from above. You need a cap for your hair.
Check-in and check-out were as comfortable as possible.