My mother and I recently stayed at the Due Fontane, and our stay, overall, was a good one. As a previous reviewer mentioned, the septic system released a foul odor into several rooms (we were on a tour and I confirmed this). The bathrooms in general were the least desirable part of the hotel. Ours was lit only by a small fluorescent light over the mirror, and the shower was like that on a boat--if you didn't draw the curtain, you could sit on the toilet and bathe! While there was a grab bar in the shower, the soap dish was way too high for someone who needs to sit on a stool while bathing (as my mom needs to do). The rest of our room was gorgeous, though, with terrazzo floors and beautiful fabrics. If we leaned out the window, we could see Giotto's campanile.
There was, indeed, a lot of noise outside at night, but hearing Florentines living their lives was kind of a kick. We found most of the staff to be helpful and really kind, as my mother injured her knee on the way to Florence and had to be helped on and off the bus. The gentlemen who worked at the hotel were right there to help. One kind front desk man refused to accept a tip, even after arranging for a doctor to come to our room. They even bent the "no food in the rooms" rules and let me bring my mom coffee, food, etc. If it weren't for the odd and odorous bathrooms, I'd stay here again in a heartbeat.

Recently returned from a stay at Le Due Fontane. The hotel is across a piazza from the Accademia and a few blocks from the Duomo, which is its main selling point. It also has free internet in the lobby which is convenient for travelers. However, the staff was very unfriendly, the rooms were very dark and more than once the odor of raw sewage permeated the building. The piazza it faces is also somewhat questionable, with a fair amount of shady characters lurking about.
They never bothered us, but some people might feel uncomfortable walking there at night. Included breakfast was decent. Overall, an ok place to stay if you're on a budget and want to be close to the sights, but for the general public, there are more charming places around for sure.

Located north of the Duomo, the hotel is a bit off the beaten track.
However, the hotel's location isn't a fatal flaw since Florence is such a compact & walkable city. We stayed at Le Due Fontane for 2 nights in late September 2003. We moved to another hotel for the remainder of our stay in Florence because there were a group of drunk men on the street below who were screaming & hollering from about 1AM to 4AM. The hotel staff told us that it wasn't their problem - they could not control what goes on outside the hotel. After additional discussion, the night manager informed us that the drunks have been partying outside the hotel almost every night for the past 2+ years. The 2 rooms we considered on what was a dark, dirty courtyard smelled musty and were inferior to the rooms on the hotel's perimeter. Stay away.