I stayed here with a friend for 3 nights in December 2015.
The reception staff were very friendly, although there was a different person most the time each of them were very welcoming, offering to have our bags stored in the luggage room until check in and helping with any questions we had. When my friend was ill, and I stupidly wasnt there, the guy on reception was lovely to her, very concerned, called her a taxi and gave her his blanket, making sure to tell me everything that had happened when I got back. Never experienced such a lovely staff member before in a situation like that.
Our room was shared for 6. It was clean and bright, the beds were clean and decent to sleep in. There was only 2 plug sockets in the room so if you can i recommend grabbing the bed next to them as sharing the sockets can be annoying. Need to take your own locks for the cupboard (if like us you forget then you can purchase them for one euro at reception) which are a good size, big enough for two hand luggage cases. We stayed on floor 6, same floor as the bar but it wasnt noisy as the bar closed early and the wifi connection was really good, only 1 euro for 24 hours.
The bathrooms and toilets were clean, quite modern actually, nice compared to other places I've stayed. They were quite dark in the afternoon/evening though when the sun moved away from the window but bright in the morning and good for doing make up in the bathroom mirrors! The shower temperature was hot as well.
There was a lot of younger guys staying at the hostel when we were there, probably around 17-18. It wasnt an issue for us but they were hanging around in the hallways, reception and outside. Occasionally they would shout at us but they were harmless and friendly enough, this hostel seems popular with younger guys of that age which isnt something we found an issue but worth noting.
Also a supermarket just opened behind the hostel which was handy.
In all this was a clean and friendly hostel, with Alexander platz and the train station less than 5 minute walk away. Worth mentioning there wasn't a lot of bars and night-life in the area but visiting Hofbrau berlin down the road is a must!