Stayed here 15 years ago in 1988, when it was busy and the restaurant was full of life, and the bar was in operation. At my visit to Oaxaca in October 2003, we took 2 rooms, charged $60 each room when hotel manager knew we intended to stay 5 nights, no room for bargaining. We were the only folks in restaurant, but I believe there were only 4-5 other people in the hotel. Food was 3rd rate for an 'established' place. Bar closed. Hotel has not been maintained - same room as 15 years ago not refreshed or kept up, peeling plaster, room still practically bare, lamps teetering, carpet/room smelled although room seemed clean. We both checked out after one night, moved around the corner to US$36 Hotel Antequera, which compared to the Senorial's pricing should have been charging better than twice Senorial's rate.
The only thing to recommend it is the protection from (the rare) zocalo noise it affords in the rooms which are buried against a facing wall.
The place needs bright paint, bright lighting, and the rooms made attractive with wall decorations or anything attractive... There is no need to stay at Senorial - despite its listing in many guidebooks simply because it has location on the zocalo... We ended up a dozen steps from the zocalo in a refurbished room 3 times better, refurbished hotel.