We spent 2 nights in Stone Town Cafe and it was a fantastic stay. I found the staff to be personable and friendly. Ibrahim downstairs is a legend and I really hope his dream of coming to London comes true!
The rooms were well serviced and maintained. Air conditioning worked fine as well. There are stairs as people have mentioned but the house staff are more than happy taking your luggage up. There is a safe for your valuables too. The owner also offered us our room for a few more hours after check out to keep our bags in, which was a very nice offer.
The only poor thing about the room was the holes in the mosquito nets above the bed, but this we rectified (using towels etc) and told the owner before we left.
Overall, do not hesitate to book a stay here!