Petra really puts a lot of thought and effort into being a host. She will communicate in advance and while you are there. She is happy to offer advice and if necessary to lend things that may be useful (a guidebook, an umbrella). She asks what you might like for breakfast (and for me at least, went out early in the morning for fresh rolls). It's all quite amazing.
You are very definitely in her apartment, and she is often there even during the day, so this place is probably best for someone who plans to be out and about a lot, and certainly for someone who is quiet but also happy to talk to others.
The room itself is beautiful, spacious, high-ceilinged, in an apartment block that is easy to access via public transport, and from which the city centre is very accessible (again, via public transport), though there are also restaurants and shopping close by.
All in all, my stay in Berlin with Petra was a great experience, and I would very happily go back.