It was a great stay and I really liked the apartment. I felt at home there (more so than in other places I've stayed, somehow!), had everything I needed and everything was very comfortable and good quality (except perhaps the cotton-filled pillows: those were not the most comfortable but oh well, they were OK for a short stay, plus they definitely weren't the worst I've seen). One other thing is perhaps that there weren't large towels provided, only small ones. But really overall everything was great, it was a super nice experience.

The wifi seemed fine; I didn't use it much, but while I was, there were no issues.

I really appreciated that the apartment seemed truly non-smoking (did not smell at all), even though, like pretty much everywhere in Europe, the hall (outside the apt.) of course smells because so many people do smoke. But in most places in Europe that I've been the apartment would smell even though it would be advertised as non-smoking. Like in most such buildings, the apartment has excellent plumbing, so you can take a great shower or bath.

Michael went above and beyond of what is usually expected by accommodating a very early check-in on a very short notice.

Location: while the avenue itself is a typical Soviet-looking one (big multistory buildings, see the listing photo), it is located literally a few minutes away from the Museum island, Konzerthaus, Staatsoper etc. It is in the heart of Berlin, very convenient. Easy public transport to/from the airport (~40 minutes) via U6 + bus 128.

Great stay, thanks very much Michael, looking forward to staying again!