Nadezda's place is in a perfect location, easily walkable to everything in Condesa and Roma while still somehow being quiet. It was the first place I've staying in Mexico City where I didn't need ear plugs if I closed the bedroom doors. It's a beautiful and unique setting with the open air layout. Nadezda provides thoughtful touches like coffee, wine and a snack too.
A couple things to consider depending on your circumstances. One bedroom has the bathroom in it and the other has to use the bathroom upstairs, which requires going up the outdoor metal staircase. It's a bit awkward so consider that if you're traveling as two couples. Also, the open air layout is beautiful, but if you have sensitivities to the pollution it can be difficult. This place is a great for a place to stay, but not really for relaxing. I don't visit Mexico City to lounge, but if you do, the furniture isn't really conducive to that.