If you're the sort of traveller that demands the highest of luxury and amenities then look away now. The Abuso has none of these things.
What it does have is charm, a great personality, the most abundantly helpful and pleasant staff, a brilliant location, clean rooms and a wonderful rooftop veranda.
I stayed for two weeks on business and came to grow very fond of the place. The breakfast is simple but delicious (fresh fruit, tasty cinnamon buns, etc).
This is a very basic hotel, let's not deny this fact. There's no TV in the room, only a communal fridge in the public area on each floor and they don't sell alcohol. But so what? Stone Town and Zanzibar needs exploring and you just need somewhere to sleep, on the subject of which, the bed was comfortable!
It's all about context and in the context of a low-price, basic hotel this is absolutely fine.
I mentioned good services. When leaving, I had a driver booked to take me to the airport. With time marching on and no sign of the driver (or responses to my attempts to contact him), the owner of the hotel offered to drive me there himself - for which he refused to accept any payment or tip. Can't imagine many other hotel managers doing this!