Pretty impressed with this place. There was a problem with our booking (think this was because of an error by Booking agent rather than the hotel). The member of staff on reception booked us in anyway and got it all sorted without any fuss.
Location is pretty good. Berlin's too large to walk to all the sightseeing spots, so you'll need to use the U-Bahn. This hotel is right by one of the most useful U-Bahn lines. It's also really easy to get to from Tegel Airport. Just use the X9 bus to get onto the U-Bahn system and you're sorted.
Breakfast was good, too.