Boussi Falafel is almost five minutes away from Nollendorfplatz. If you are lucky enough to arrive there in a sunny day, outside tables are a good choice, as you could look extensively at the people coming and going around this busy area of Schöneberg. I was there around 2pm, and there were many people chilling around, not all of them looking as tourists.
The place looks clean and shiny-white and the food is tasty, healthy, veggie. The preparation doesn't take too much time and everything looks very colourful and natural. Apparently, the place is Lebanese, as the vendor explained me when I tried - loudly against the loud Oriental music - to find out about the preparation method of the hummus. For instance, I have a big problem with the Turkish hummus, too solid for my taste. This one was good, not too spicy and oily, but again, nothing to complain against.
I ordered a falafel plate and I was satisfied with the proportions, the taste and the combination. As for the price...I paid 5 Euro for all.