The flat has well enougth space for two people. Small, but very cozy. Compairiyg with previous March Rome visit experience we expected cold flat during the night, but this place is equiped with heater switched on by timer (approx. at early morning), so you will not stay in cold in early spring :)
Host does not charge for city tax 3.5EUR per person per day (I assume it is included into the price).
Conserning hot water supply, it's equiped with electical boiler with timer as well and with limited volume of hot water in it, so if both of you like to stay for a loong time at the bath, one of you will probably be lack of hot water ))
The flat itself is very comfortable, has a lot of space for luggage, clothes, etc.. Location is perfect for those who like shopping.
If you plan to rent a car and travel around, you'l not be able to park the car close to the building as soon as this flat is located inside ZTL area where regular (rented) cars are not allowed to enter.
Anyway, this place worth of it's cost, highly recommended!