It is a unique and amazing place to stay in Florence, it's exactly what it appears to be from the photographs.
There are a few things to bear in mind though.
Check in is not 11:00am, as this is before the cleaners have come in. You can drop your bags off from but can't fully check in until after the cleaners are done. For us that was 2:00pm.
The place is kept clean (we saw the cleaners when we tried to check in at 1:00pm) but because of the floor is concrete it might look dirty but that's just the nature of the material.
The downstairs room with the pool is very humid but as long as you keep the door shut the rest of the apartment isn't affected.
Would 100% recommend for a short stay but maybe not for an extended period.