Hotel Pension Rotdorn is not recommendable in my eyes.
When we phoned the owner and asked him whether they had quiet rooms, and he told us that it is a family-run business situated next to the Grunewald in an idyllic area. In the end, it was neither idyllic nor quiet because there is a six-lane street running just 20m in front of the house. So if you do not insist on getting a room to the rear, you have had it!!!
We complained to the owner about our situation because we ended up in room no. 1, which is in the front. Though I had asked for a quiet room beforehand, he could only offer us several rooms to the rear at a much higher price. Besides, we would have had to move twice between rooms within one week, always paying extra for the room cleaning. Since this was not acceptable to us, we decided to leave. Threatening to involve his solicitor if we left and asking us to pay 50% of the price for one week, we stayed on.
In the end, we paid 60€ per night/room. For that money, you would at least expect a nice breakfast (in some pensions you even get a breakfast buffet), but what was served there was a mere collection of cheapest the Aldi (Germany's cheapest supermarket) ingredients, although they also served fresh rolls that were quite alright.
When you think of going to Berlin, you better end up staying in the former East Berlin, where you get better value for your money.