We had a good stay at Donovan's. The apartment is very well located, 5 min walk to Waterloo, and also close to the South Bank ; but still in a very quiet neighborhood, which appears to be a good thing at night !
The room is great and perfectly clean, and the bed is super comfortable. Donovan is a very nice host and he let us leave our luggage until we had to take our train in the evening.
The only negative aspect would be that the apartment is a bit busy given there is another room to let. At the end of the day there are quite a lot of people in the apartment, so it is not always optimal regarding the feeling of privacy and intimacy ... But it was more than OK for our 2-night stay.
In a nutshell, Donovan's place is a good deal for a short stay in Central London !