My stay was really good, the apartment was impecable, clean, organised down to the smallest detail. Much better than many hotels I've been to.
The only - but big enough of a problem I found, was with the communication. I was unable to access the Internet, sent them a message and never got a reply back. Same happened with a late check out request, which resulted in me being waken by the cleaner at the door and I had to rush out.
They said they don't work during weekends, hence the lack of reply, but I'm sorry that's not good enough of an excuse. You're either providing a service, or you are not.
Everything was really high standard, but this bit was clearly incompatible with everything else, and ended my experience in a really bad note.