My wife and I were there for 11 days. We loved the (studio) apartment and wouldn't hesitate to come back. We thoroughly enjoyed our stay.
The location is outstanding with just about everything you need close by. A convenience store (OXXO), food stands, restaurants, barber, dry cleaner, on-site laundry and even a laundry mat just a block or two away.
It's also a short 15 min walk to the Zócalo, El Palacio de Bellas Artes, the Tequila Museum and metro stations.
As for the place itself, the apartment (we were on the 4th floor) is perfect for two people. It was very clean and nicely decorated with everything we needed.
I did work remotely there for a few days, and the internet was fast and reliable, not one single hiccup. Not a lot of outlets though, so if you have a lot of devices you'll need to bring a power strip.
The apartment has lots of natural light due to the floor to ceiling windows. It's pretty quiet as long as the windows are closed. They keep out the vast majority of the noise, but the street the apartment faces is very busy at times and occasionally things get really loud and the noise seeps into the apartment. At night it was pretty quite as well.
The gym has some equipment that is need of repair, but other than that I have no real complaints.
We felt safe walking the streets of the neighborhood. During the day the street is very busy and at night they are well lit with a few people out, mainly food vendors. Granted we weren't out in the streets that late or for that long, but we never felt in danger of any kind.
I think it's a great place to stay and I totally recommend it.