We booked a double room on the "Hotel" part of the building.
The Hostel is quite near from the U and S-bahn, but even if it's officially in "Mitte", it doesn't have a very central location. That said, it's not far from the animation with the subway.
Room was clean, but staff attitude was disapointing, especially for Germany: quite rude guy at the reception, and the lady that cleans the room entered twice our room before check-out time.
For the same price, I know it's possible ton find better in Berlin

This hostel is fine if all you want is a cheap bed for the night, but it isn't personal or friendly so if you want to meet people, look elsewhere. They also charge a lot for extras - internet was slow and very expensive and sheets are 3 euros extra. It is part hotel part hostel and feels very industrial, there is no personality at all, but the rooms are a good size and have a big locker for each bed. You can also block additional beds in a dorm if you want it to yourselves.
The bathroom was nice and cleaned everyday, and the location was not bad, quite central and 5 minutes from the UBahn station.
This hostel is good if you're travelling in a group and want to keep yourselves to yourselves, but if you're a lone traveller I would recommend the Schlafmeile Hostel in Friedrichstain.

The hotel/hostel is fairly easy to find – 400m or so from Heinrich-Heine Strasse U-bahn stop. The area is fine – it’s mostly populated by students and it’s only further down the road in Kreuzberg that you hit the cheap food joints of the Turkish district – not Arabs, as someone mentioned in earlier reviews. Amenities are pretty good in the locality, and Alexanderplatz is quite close on foot.

The A&O is pretty much no-frills. The staff were ok. The room was bare with just two twin beds, a TV, a wardrobe, a wooden chair and a small table. The bathroom was surprisingly well-equipped, however, with a soap dispenser, toilet-seat changers, sanitary bags and a terrific shower.

Yes, there are lots of kids and it can be quite noisy, but for one night, it did the job superbly well and I’d happily stay there again if I’m in Berlin for just one evening. However, a longer stay and I’d opt elsewhere since the amount I paid - €39 – is pretty pricey for what I got. Breakfast was €4 extra, as is internet, wi-fi and practically everything else....nothing seemed free of charge. There’s an ATM machine on site, as well as a stamp machine and a bar, canteen for dinner. But for all the added-amounts, I’d stay at a B&B.

The hostel is brand new so smells of Ikea and a few of the lifts still dont work. Got woken up one morning by the noise of construction! Very vibrant atmosphere with lots of young travelers staying here. Staff are not as bad as people are making out, was very helpful to us with directions. its a 10min walk from central station which you will need to get around Berlin, although the city centre is only 2 stops away on the train. Rooms were very basic, but very clean and the TV has english channels! Internet in the hotel is a rip off same with drinks etc but overall if you need a place to stay for a few nights in Berlin its an okay place!