Hotel Otto is a pleasant little hotel in the Charlottenburg area of Berlin. The hotel was clean, modern and at an excellent location in walking distance from Zoo station and Kurfürstendamm. There are many nice cafés and restaurants nearby, but despite this the area is quite.
While my stay was fine, I found the room to be slightly warm and there is no air conditioning. I was there in late spring, so not a big problem, but I imagine this might be an issue in summer. I was on the ground floor, and the sound insulation to the street was not brilliant, but this was not too disturbing.
I did have a little note on the housekeeping service. On my first morning there, housekeeping wanted to come in at 9.30 in the morning, which I find rather early (I had not hung up a "do not disturb" sign). On my last full day, I went out for breakfast hoping that housekeeping would come while I was out. They did not. I returned at about twelve and stayed 1.5 hours with the "do not disturb" sign hung outside. I then left and returned in the evening. Housekeeping had left a note saying that due to the sign, they had not cleaned the room... Not a big deal, but I found this a bit odd considering it had only been there for under two hours.
Apart from these small things the stay was fine.