Two things we didn't enjoy our stay. One was the wifi sucked. Nearly no wifi. Both of our iPads didn't pick up any signal. In order to use the three desk tops, one needs to deposit the passport to borrow the mouse. The desktops were not fast either and if you relied on the Internet, I suggest use outside cafes to help you.
The second was the loudness. Maybe it was just during our stay or our room facing the street. The walls were not sound proof at all. All the crazy laughters from next door and the rock and roll music from the bar street kept us up all night. We had very poor rest. Having said that, we are early 30 year old couple. If you were younger and single, this might suit you much better.
Hostel Regina was one of the three hostels we stayed in Mexico. We stayed for two nights. The location was superb, with only a few blocks to zocalo and right at the corner of a busy bar/restaurants street. You will easily find plenty of choices from street food (a must try street food stand right cross the front door) , to cafe, to several convenience stores.
There is a very cute roof top Terrance and at night it transforms into a bar, packed with folks.
We really loved the breakfast spot, not for the food, since it was only one bread and coffee. We loved the decor and how interestingly odd to have a breakfast in a night bar type of joint. The staff were super friendly at the spot.