The Colorado Trail had to have been what they were talking about when the phrase "the Great Outdoors" was coined. Every possible, element of terrain, from the easy hike to the challenging cliff, is represented on the 28 segments of the Trail.
As a hiker, you may encounter as many as 15 mountain passes along the length of the trail, and it's possible that you'll face thunderstorms and snowfields even into mid-summer. The next day, you're likely to hit a pond or lake in which to cool off from the beating sun.
The roads are traversable (they're mostly dirt and rock), but look out for hazards such as exposed ridges, high water and washed-out bridges. No matter where you are, you probably won't see many signs of civilization, but you will have the constant backdrop of the Rocky Mountains.