The hostel is new, so all the facilities are pretty good and the rooms are in good condition. Most nights there are organised events for people to join and go out - it is a good way to meet people and to see clubs or bars that you might not necessarily go to on your own. It is definitely a 'party' hostel so the atmosphere on most nights is good - if your looking for somewhere quiet i wouldn't recommend it. The only main disadvantage is the lack of air con - as in the summer it can get hot.
It was very close to the train station so definitely a great location in that respect, however the area is not that nice and therefore doesn't really give you a great experience of Florence. Our room was situated across the street - the rooms are split up so its harder to meet anyone, it felt a lot like living at a boarding school. The outside area is nice, with sofas etc to chill. There was no aircon/fan in our room though which was unbearable, so we had to borrow a fan from the reception.
The hostel itself is located quite a way away from the main city in Nice. This isn't such a problem during the day - there are trams that run pretty regularly and a shuttle bus that picks you up from the last stop, however for going out this can cause some problems. The last shuttle bus is at 2 & taxi's are scarce so be warned. The hostel is friendly and has a very sociable atmosphere - the bar is a really good place to meet new people. Our room was nice but the air con didn't work.