We stayed here last December- it's a ten minute SBahn train in to Alexanderplatz and is very modern and unusual. Breakfast was fantastic, great bar, on the river and the staff were all young and enthusuastic. It's not the sort of place we normally stay in as we usually go for older more traditional style, but we chose it as it was near the music arena we were attending and we'd certainly go back.
www.nhow-berlin.com/en/