Really enjoyed staying at Lucas and Claudia's flat, it's a great space and really well located, close to the centre and near to many key sights, as well as restaurants, bars, clubs etc so plenty of entertainment in the area. You can walk pretty much everywhere from the flat which is good as helps give a feel for Berlin rather than having to take loads of public transport.
The flat itself is really nice, big kitchen to relax in at the end of the day and everything you could need is provided. One slight point - although there are two bedrooms one is a living room with a sofa bed, however this was perfectly comfortable but perhaps something to be aware if you are coming with friends rather than as a couple as we did.
Lucas made us feel very welcome and provided us with all the information we needed, arrival and check out was easy to arrange as communication was quick and reliable and there is further info on things to do in the flat - all in all would definitely recommend!