On the plus side: comfy bed, clean, colorful decor, huge bathroom, lovely little courtyards and wonderful shared spaces especially if you like to chat with other guests.
Down side: if you like all the modern conveniences and extras, a few are lacking so if it's important to you you'll go elsewhere - ability to control temperature (the whole building probably set at 72 or so, glad I brought a blanket - I tend to get cold), good water pressure, toiletries other than one bar of soap and one shampoo, sink faucets that combine hot and cold water. Guests make their own coffee one cup at a time. There can be a line up. Fortunately guests upstairs quieted down at 11 p.m., with hardwood floors throughout an old building you can hear a lot.
All in all I enjoyed it and would stay there again, but I like unique places as long as I'm comfortable.