Alexander's place is nice and neat and in a nice area that is well connected by buses (although not too close to S-bahn and U-bahn stations).
Alexander was easily contactable and made sure we had discussed the key collection and house rules.
The only downside that was that we had to collect the keys from his friend who was about a 40 minute commute away by public transport and we ended up taking an Uber.
As for the key drop off, as we were leaving early, his friend had to collect the key from us late at the night the following night which means that, in the case, we had to leave the apartment, we could not re-enter.