Where to start; worst problem is probably that the company advertises with it's central location and even mentions on Expedia that it's located in the Mitte district... Don't be fooled, it's not. It's a 15 minute walk to nowhere, though at nowhere you at least find a subway station. Still, the neighborhood itself is amazingly uninteresting and appalling, ie ugly and at night full of drunks on streetcorners.
Next up, the horrible, ill-making smell which for some reason comes from every possible bathroom in the hotel. It was explained as some summer-based problem with river water coming up (?!?); Still, summer was gone and the smell remained. Regardless, how could one accept any excuse??
Rooms only have double twins, which leaves me wondering: is there actually anyone aside from a bunch of students travelling together that rather sleep on a smallish twin bed??
Minibar is advertised as complimentary, though you are chargest for every refill (last time I checked, that was not the definition of free). Breakfast is so expensive, you might expect caviar and champagne. While the selection is definitely decent, it in no way compares to the outrageous prices. In general, food appears to come at a price which is quadruple it's value.
Staff is mostly uncompetent, albeit somet are somewhat friendly. However, the front office manager is probably the most unfriendly, uninterested, arrogant, rude and uninterested person in the world. The kind of person that intends to make you feel sorry for any inquiry you might have dared to ask.

Anything positive about this hotel? Well, the wellness center is ok, and they did make an effort to be trendy (endresult however, they failed somewhat). Well that, oh yeah, and they are right on the banks off the Spree, however if you are not a river fetishist, this will not make up for all the things it lacks. Stay away from this place!

Stayed at the Adrema at the end of July 2011- the hotel is ok, staff are friendly however location is not ideal!
The hotel itself was good, breakfast was nice and the restaurant served good food.

We loved this hotel and will go back there when we return to Berlin. The view was lovely and the hotel staff was certainly accommodating. Everything was spotless and there were many extras.

I stayed at Adrema for 2 nights on a business trip. The location for me was perfect, as I had a business meeting very close to it. If you go to Berlin for tourism maybe it is not the perfect location, but it's full of bus lines just outside the door and reaching the Turmstrasse metro station is a 15' walk. One valuable thing is that it's quite close to Tegel airport: the last day I had an afternoon off, so I dropped my luggage at the hotel, toured the city centre as much as I could, then I came back to pick the luggage and in 25 minutes I was at the airport using public transport!
I had a single room on the highest floor, with magnificent view on the spree and on the surroundings. The room was clean and nice, I enjoyed the 'glass cabin' bathroom a lot. The breakfast was perfect. The personnel very helpful. Would definitely recommend it.