It was my first ride of the Chief Sealth Trail. All 3.6 miles of it.
My initial thoughts were it's really quite unlike most rails-to-trails trails in that it's quite hilly, it's also not very practical for transportation. I had my single-speed bicycle on it, and there's quite a lot of steep sections. I remember seeing a post complaining it wasn't straight, but it obviously curves to make it easier to climb. I was amused thinking about young kids trying to bicycle it. It was during the day and I didn't see see any bicyclists, just some walkers. I don't think there would be any bicycle commuters come evening.
On the plus side, there's some unobstructed views off east of Lake Washington and Mount Ranier looks lovely, but the power line towers cross the view a bit. And it is fair training ride, but would be improved if the sections of trail weren't continually criss-crossed with roads.