Tanner Trail is a challenging hike in that, at least for the first few miles, the uphill is fairly steep and slippery. Lots of loose dirt and rocks since this trail is also used by dirt bikes. Good hiking boots are a must and trekking poles are helpful as well. Also, you need to really keep an ear out for approaching dirt bikes and be mindful that if they need to pass you on an uphill, because it is very steep and slippery, they will need to really be on the gas thus spraying copious amounts of dirt and rock from their rear tire in your direction. We had no issues and the guys on bikes that we saw at the trailhead were looking out for us on their way up. Above the slippery section however, the trail gets into more trees and has some nice views and less steep uphill. We are relatively new hikers, just hitting 50 years old, but in better shape than most our age. We went about 5 miles up before turning around and went for about 4.5 to 5 hours. If you are in decent shape and good on your feet you should be good to go. Not a very technical hike.
Hiked to the halfway point and back in an afternoon. The trail is essentially a 6 ft wide or so, ATV roadbed. That said, you can't get lost and the terrain you traverse is scenic and interesting, especially the varied rock formations. Pinion pine are common as the trail begins, but as you ascend these give way to ponderosa, spruce and white pine--all very nice. The trail up is one long ascent, but is not too steep. Certainly handable by the experienced hiker. Would make for a good overnight backpack hike to go the full length and return for a 12.5 mile round trip.