My favorite hike in the DFW area, yes some parts are level, if you want exercise take Canyon RIdge out and back at a decent pace then come back and tell me how level the terrain is, we always see wildlife.  Last year in the snow we watched a Great Horned Owl along the Forked Tail Creek trail, from the Boardwalk we have watched Osprey fishing, lots of deer, get away from the Boardwalk and Nature Center for solitude, in such a small area the eco-diversity is amazing, if you get bored go watch the Priarie Dogs or visit the Nature Center