Alan and Kasia's place is as described and made my trip to Berlin an absolute delight!
Alan went above and beyond to make me feel welcome and even provided a book of things to do in Prenzlauer Berg and other neighborhoods in Berlin, complete with maps and personal recommendations based on my preferences.
And more than anything else, at the end of a long travel day, I always had a great home-base where I could rest up.
You should book a place with Alan and Kasia -- no questions asked. They'll help make your Berlin experience even better.