The only negative points would be the lack of a lift, a problem if you're travelling with heavy luggage (not my case) or you can't climb stairs.
The WiFi worked fine within the room (there was an AP in my room), but had very poor signal in the terrace, just above my room.
The breakfast was average. Mediocre coffee and not many choices, but I just have coffee and toast for breakfast, so that was not a problem at all.
First of all, the staff was extremely helpful and welcoming. They did all they could to make our stay as pleasant as possible.
The mattress is also worth mentioning. In my opinion, the bed is a key element, and the beds at Hotel Studio were the most comfortable I've seen in a while.
The views from the terrace and the rooms facing the fortress are simply amazing.