I have hiked sort of casually in the past and this summer did the longer option at Starved Rock and some local other trails....this one we went to because of the "moderate to high" difficulty. It made all other trails look like a cake walk. The workout difficulty was great---nice and painful-- possibility of danger made it more fun. We did not anticipate the mosquitoes (see...hiking nube) so I didnt bring bug spray. We could not stop to catch our breath for more than 20-30 seconds without being attacked so we had to keep moving pretty fast. We sort of jogged up the hills and were careful coming down---cause in this place if you get hurt...you are screwed. If it weren't for the darn flying boodsuckers, this was a fantastic beautiful forest hike. I'll go in the cooler months or with a bath in deet next time.
Love this trail for hiking and mountain biking. For hiking, it is awesome with lots of ups and downs and loose rock and roots (also why it is a challenging but fun mountain bike trail). I love the workout created by the short hills and being in the woods 90% of the time. It does get buggy. Also, there are horses and bikers sharing the trail.