On a kayak trip down the Grand we hiked up and came down this canyon. Bailed where it pinches down and there is a mandatory rappel or maybe 5th class downclimb into a dark chasm. Looks like what is listed as rappel 3 on this page. What a place!
We did it in two days. Started around 7:00am from the rim, arrived at Deer Creek Camp at 1:30pm, finished the canyon at 6pm. We then woke up at 4:30am and hiked out and checked out Thunder River along the way. We reached the top around 1pm. I would recommend doing it in 3 days so you can avoid hiking the upper section in the heat of the day. Amazing trip all around. Definitely worth the effort.