Staying at Natascia's place worked out well. It's located in the ever-increasingly-hip area of Neukölln, specifically close to Weserstr. where a lot of Berlin's best bars are located. The U-bahn is probably about a 7 minute walk away and there are loads of bus connections nearby. The flat itself is nice, although there were some slight problems with the shower (the head wouldn't stay in the same position). All in all it's a wonderful little flat for a getaway in a non-touristy part of Berlin. There was an initial hiccough with when I could check in but Natascia worked very hard to fix this and quickly found a solution (a friend gave me the key). Anyway, a lovely stay indeed. Thanks Natascia!