This is an easy "out and back" hike with great scenery of waterfalls, ferns, and rocky outcroppings. It's quite popular with easy vehicle access at the trailhead, so plan to see alot of other hikers and is part of the Pacific Crest Trail - this is not the trail for you if you're looking for solitude.
Bring your raincoat. Watch your step as you're hiking, the rocks on the trail are slippery and losing your footing or stumbling is not a good idea on a narrow trail with a long drop to the creek bed. GPS occasionally will lose signal in the walls of the gorge.
I did the 26.5mi loop that takes you in on the Eagle Creek trail to Wahtum Lake, where it then meets up with the Pacific Crest Trail. The Eagle Creek Trail is actually not "part" of the Pacific Crest Trail, though some PCT through-hikers choose to take the Eagle Crest Trail through that part of the state because it's a nicer hike (waterfalls, etc) than the actual PCT route, which goes up on the Benson Plateau to the NE of the Eagle Creek Trail. So, to get to the Pacific Crest Trail via the Eagle Creek Trail, it's more like 13mi in and then a junction. Definitely recommend this trail system though.
http://www.portlandhikersfieldguide.org/wiki/Wahtum_Lake_via_Eagle_Creek_Hike Visited on Aug 16, 2011