We spent 4 nights at Etienne's place for our annual visit to Berlin. Check in was flawless as was communication before our stay..
The room is self contained with it's own shower/WC and washbasin and also has it's own private entrance which makes for full independence. You'll find everything you need for a short stay, and you have Prenzlauer Berg and Friedrichshain almost equidistant. Be sure to head for Friedrichshain 'central' for an evening as the choice of food is much more interesting and varied than the more obvious option of Prenz.
Be aware that the room is top floor and a few stairs to negotiate, but for us this is no problem - and the bonus is that you get a great view of the 'Fernsehturm'..
All in all, Etienne's place is ideally located with multiple tram and S Bahn stations at it's doorstep (tip - you can reach Alexanderplatz with a 'short hop' tram ticket which you can buy in carnets of 4 at a discount in advance at €1.40 each instead of €1.70). There are bicycle hire places nearby for around €12 a day.
We would happily come to stay again, and you can expect friendly hosts, and German, English and French are spoken I believe..