There are many a kebaberie in Berlin. Imren is reportedly the best around serving excellent layers of beef marinated in milk and cooked with lamb fat. Unfortunately it isn't the most convenient to get to and so the best chicken is supposedly at Mustafa's. However this has queues (sometimes excessive apparently) and so K'Ups is meant to be as good or perhaps better. And a more convenient location for staying in Mitte too.
They only serve a chicken kebab (for meat) or alternatively halloumi. They come interestingly with not only fresh salad and herbs, but also grilled potatoes and vegetables which have been cooked and then sat under the meat. There's a very mild chilli sauce and all is topped with fine feta. The overall result is a very flavoursome roasted chicken with both savoury cooked vegetables and fresh light salad. It's a great combination. Similarly the halloumi version was as good with fried salty cheese.
It would have to be the best chicken kebab I've had overall. I wonder how a beef one would fare...