Betty's place is absolutely great. I stayed there for about 6 weeks this summer. It was quiet, clean, and private. The annex has four bedrooms, and although they were all occupied during the majority of my stay, noise was never an issue. I really enjoyed cohabiting with my neighbors in the casa anaranjada :) The area is very residential, but just a block off of the eje Central Lazaro Cardenas that goes downtown. The center of the city is best reached on the metro blue line, which takes admit 15 min, and the nativitas stop is a 10 minute walk away. Lots of little restaurants in the area, and two markets: independencia and portales (the larger of the two). Betty is incredibly welcoming and attentive. She made sure that myself and other guests had all we needed at all times, and was which to reply to text messages always. She even helped me get help when I was having computer problems! She has a sweet but nervous dog Lola, who rarely barks. Cleaning is done once a week, with a change of sheets and towels. My room as very bright and comfortable in all senses. Hot water 27/7, good water pressure. Each guest gets there own cabinet for storing food I the kitchen, and the kitchen was always kept very clean by the guests. I prepared about half my meals there with food bought from the market.
I recommend 100%!