We followed frequent cairns the entire way to the ridgeline. In addition, there was a well defined path the whole way except for the sections over rock. The well-defined route matches that of gpsjoe which differs from Joe Bartels only near the top. If you're not a mountain goat, take the path near the top that tends west (the one that matches the gpsjoe track). It's well defined and easy--it even has mini-switchbacks. The drawback is that you hit the ridgeline farther west and lower.
We didn't see or didn't notice the "10 foot wall" perhaps it's in this upper section.
I'd rate this currently as a 4 to 4.5 with route finding as a 2 due to all the cairns. It's similar in difficulty to the route up from Carney Spring or the route to Flatiron. It looked to be harder coming down than going up.
There was only one steep section about 3/4 of the way up--but it's less than a quarter mile. It had scree on top of solid rock but you can spend most of your time on solid rock by carefully picking your route. There were two sets of cairns through the scree. One set went pretty much straight up the hill (matching the gps tracks). Another set of cairns skirted the slope to the left nearer to the creek bed but these cairns soon ended. This lower route over bare rock bears more investigating. (It seems to match the route proposed in "60 Hikes within 60 miles of Phoenix": "If you find yourself on a steep slope covered in scree and loose rock, you've gone to far to the right.")
The views climbing up Hieroglyphic Canyon were a lot more interesting than I expected. (There was water flowing and even ice in shaded areas of the higher elevations.)
One reason this hike was so easy is that we left the trailhead at sunrise and made it to the ridgeline before the temperature hit 50 degrees and before the sun hit us.
This is the second time that I've left the Hiero trailhead about dawn and have run into a bridal party headed down. What wedding day rituals are taking place at dawn near the hieroglyphics?