The apartment was as described. If staying in the summer, you may want to bring a fan to keep cool as there is no air conditioning. There is also a 5% tourist fee that Berlin imposes on private rents that I hadn't seen mentioned in the property description, so be prepared to pay a few extra Euros (in cash) when you stay. We were there for 5 nights which was €12.50.
The location is fantastic, only a few stops on the U-Bahn from the center of Berlin and easily accessible to all the popular tourist sites. There is also a local Reve (supermarket) about a 10/15 minute walk from the flat which we visited nearly every day for things for our evening meals.
Ekhart greeted us on the day and gave us a short tour of the apartment and mentioned a few house rules etc and didn't really bother us after that but did say he was available to call if anything was wrong.