Used on a couple of day hikes so far, worked well. Was especially useful for assessing total distance traveled, and for emailing waypoints and tracks for import directly into Google Earth on another computer.
Be aware this app is no substitute for a proper and up-to-date trail map. The two maps I downloaded were over 30 years old and showed very little of the trail systems in the parks I visited. For example the Mendham NJ quadrangle was last updated in 1981 from a 1976 aerial survey. Finally, map handling appears processor intensive; each pan or zoom-out involves a 1-2 second delay on an iPhone 4s. Im OK with all this however, no regrets.
Sondergaard about iHikeGPS : Classic Topo Maps, v3.5