Great day hike with a nice 360° view but check the weather beforehand. Note: there is now an alternate access via Meadows Lane to the trailhead - not sure exactly when or why the other trailhead closed down. If you park at the Meadow's lane Crabtree falls parking lot, the trailhead for spy rock is about 0.5 miles away.
Hiker beware: Meadows lane ices over really bad and is impassable without chains (see pictures). My planned 7 mile hike turned into around 12 miles starting from Route 56. I would definitely recommend but it might not be the best hike in the winter due to the access road conditions.
The pictured map is near the summit.
The AT portion of the map which goes past Maintop Mtn is what you hike in and out on - eventually it connects to an access road and Meadows lane.