We stayed at the Villa Bismarck for 3 days in August whilst visiting Capri. There was lots of space for the 4 of us - with 3 bedrooms, 2 bathrooms, a kitchen, a dining room and a large outdoor space - and the standard of accommodation was very good. Air conditioning was excellent and we were provided with fresh towels every day.
The wifi wasn't great, there wasn't enough hot water for consecutive showers and breakfast was pretty average.
Overall though, given the size of the island and the price we paid (a lot) we were really pleased with what we got.