Hit this trail for the first time today and did all three of the trails (Fern, Canyon, and Panther Hollow) out and back. I started at the bottom with Panther Hollow then took a detour down Fern and came back to Panther once I reached the end. Once back I continued on to Canyon which is by far the most difficult because of the multiple sets of steps/elevation change. Got a solid burn going and the heart rate spiked for sure. I recommend starting at the bottom just because I wouldn't want to do an out and back hike leaving that climb for the end when my energy is spent. Once I reached the top I went back and took off, but I intend on going back soon to check something out; near the top of Canyon there is an unmarked trail that cuts across. On my way back down I took it as a detour for about 10 minutes before turning around. I'd like to find out where it goes and intend to. All in all it was a great time. Stopped to sit in the spring for a second and the cold water was great. Only complaint is an off leash dog that was pretty aggressive.
Trail is difficult but rewarding. The river runs right beside you for the majority of the trail. Lot's of stairs with enough rest stops to catch your breath and enjoy the view. Lots of dogs on the trail (which I love) but there are parts of the trail that are narrow so keeping your dog on a leash is recommended.