This is a beautiful place and a great workout. I'll be returning to hike it again!
I began my hike at the Boardwalk trail head just before sunrise. I made my way up to the very top of the trail (taking a small journey off of the main trail to check out what looked like a side trail but ultimately that went nowhere special) and turned around at the upper trail head on River Place Blvd and made my way back down. On the way back, I turned and hiked the Little Fern Trail segment. I'm glad I did: That segment has some of the best-looking water features. When I got to the trail head for that segment I turned around and went back and hiked out the way I came in.
This was a good workout! BRING WATER! I'm glad I brought more than I thought I would need because I drank it all. There are many, many stairs and I certainly felt it a day and a half after the hike. This trail isn't a loop, so you'll have to turn around and hike it again to get back to where you started, or have someone come and pick you up at your ending spot. I recommend doing what I did if you don't have someone to pick you up: Start at the bottom, go to the top, come back down to the bottom. That way your return trip to your car is mostly descending stairs.
The trail was pretty wet and muddy even though it hadn't heavily rained (to my knowledge) before I went. Keep this in mind along with the fact that you have to cross a creek several times and wear appropriate shoes (ones that you don't mind getting covered with mud).
For the first hour or so of my hike I didn't see but two other people. After that the place started getting more busy with people and their dogs, so if you want to hike for solitude this isn't the place (I didn't mind, though).