Guillermo's place is beautiful and centrally located. We stayed for 4 nights and it was perfect. Just a short walk to the metro station and many sightseeing areas like Condesa, Roma, and Chapultepec Park. There was a security guard up front at all times and I loved all the facilities the building offered! The place was clean and we felt safe at all times. The hallways do echo so you may hear your neighbors on the weekends, but they are generally respectful and quiet during the evening.
I did not get the chance to meet Guillermo in person but there was no need. We were in contact the whole time on Whatsapp. He was accommodating when our flight was delayed, offered many recommendations, and checked in occasionally to see if things were going well. Thank you!