We stayed at Javier's place during our trip for the Berlin Marathon and it was perfect for that occasion and would be great for any reason going to Berlin. The place was very clean and big. Javier was great by letting us store our luggage a bit early after we got in at 6am from our train ride in from Amsterdam before we were able to check in at 1pm. Trains were easy to catch from the Nordbahnhof S-Bahn nearby. Javier was also very good at helping us with any questions he would respond via email within a few hours. Just an FYI for anyone staying there, it's about 25 Euros to Tegal Airport from his place. He had lots of Berlin books in the apartment and some places to eat nearby and a business card for the taxi that we used. I would definitely reccommend this apartment to anyone and would stay here again if I do another trip to Berlin.