Location was superb, hard to ask more (take into account that living in city center includes some street noise :)). Apartment was also quite well equipped.
One downside was noisy neighbours and thin walls. I was "lucky" and in the next room there were living British guys, who at one night coming from bar around 3 AM thought that it's good time to listen music, laugh, sing etc. Although I must admit that against singing not too many walls would help.
Host was great, he had prepared go to list of attractions and museum free hours.
House rules - not sure if it was bad translation from Spanish, but there was one point that you should not turn on lights between 12 PM to 10 AM. I guess people moving in dark might make more noise... Not sure what was this point motivation :)