This hotel was conveniently located along a tram line. The stop is nearly right in front of the hotel. I went in the fall so the weather wasn't too warm. I don't know how the building would fare in hot weather given that I didn't see any air conditioning in the rooms. The wi-fi only works in the lobby. Sometimes the signal gets to the upper floors, but otherwise count on it only in lobby. The reception and public areas close at 10:00pm so if you want to use the wi-fi at night, you will have to sit in the stairway. The hotel sells the various transit passes and museum passes so its convenient in that way too.

This was our first hotel in our European vacation. It was clean, quiet, and well situated in Prenzlauer Berg, which is a neat area. There was no air conditioning for us, and it was a bit too loud with traffic noise to have the windows open. With them closed it was plenty quiet, and the little fan brought us through the night. Breakfast was ample and good.

We stayed here for 7 nights so it was a great deal - Euros 100 / night with breakfast and WIFI included. Large rooms, very clean, great front desk with all types of info and they are selling transit cards and also speak fluent English. Very god breakfast (the room may fill up and you have to eat in the small bar area). a tram stop outside the hotel is very convenient and gets you anywhere. Great restaurants around the hotel and no problem walking the area. The front rooms can be noisy - from the tram.

I stayed at the Kastanienhof for the third time within a period of four years - as expected, I was met by the same friendly staff, calm atmosphere, and a decor reminding me of visiting my grandmother. This hotel is cozy, nice, and slightly at odds with its trendy neighbourhood, as time does not really seem to have passed since the 50s at Kastanienhof.
Large, quiet, clean and comfortable room, excellent breakfast buffet, and great central location - only drawback is that the hotel is slightly pricey compared to other hotels of similar standard in Berlin, and there is no wireless internet. (Which, assumably, is due to that most visitors seem to be 50+ and not business travelers.)
In short, if you're looking for a friendly retro atmosphere, this is for you - if you're a younger person or in need of business services, you might feel a bit out of place.