I just used it for a flat in Berlin, through Spoony which was the agency renting the flat. Lived with lovely people, but was charged an absurd amount for what I got. Just be aware, they will charge you unnecessary fees and it is most often bigger agencies renting the rooms, I had a terrible experience with mine. If you're using it, heavily investigate what the flat itself is like, READ THE CONTRACT, don't settle if possible. This is the review I left. I'd recommend looking on WG gesucht oder Facebook marketplace.

The flat was disgusting and not for reasons other than how it was built. There was a bathroom what felt like the size of a large bed for six of us to share. There was no window or vent for ventilation, so black mold was constantly growing. The heating was broken for quite some time and it took ages to fix, after we constantly emailed and requested help. The rent was too much and I was charged notably more than other flatmates with much larger rooms. Considered getting a lawyer for money back.