Julian's place is absolutely amazing.
The location is PERFECT for exploring the city. It's a short walk from Reforma, which can take you to the Angel de la Independencia, the Bosque de Chapultepec, and more.
The room itself is a great size for a solo traveler. It has a fridge, a rack to store clothes, a mirror, a desk/chair with a light, hangers to hang up some clothes, a big window with curtains, and a bed.
The bathroom, sink, shower, and washer/drying lines are all shared with the other residents. Usually they're all free, so it isn't an issue at all. And throughout the week, a maid comes and mops the floors/cleans the bathroom and all that.
I felt 100% safe at Julian's. All of the residents I interacted with were really awesome people. If you're really worried about safety, your door locks as soon as it closes. There is no lock/unlock feature. So make sure to always carry your key when leaving the room!
The room is at the top of the complex. So you have to take about 4 flights of stairs up to get to it. It's tough at first (especially when carrying luggage), but you get used to it. It actually helps you acclimate to the high elevation in Mexico City faster (or at least it did for me).
If you're a solo traveler/first-time Mexico City traveler, I highly recommend Julian's place!