This is a pretty steep (720 m elevation gain) trail most of the way, and the round-trip (9.8 km) takes a solid four hours (including a short break for lunch at the top). Make sure to take enough water, especially on a hot day, because you'll be sweating enough to need to re-hydrate. We were almost entirely under the cover of the forest canopy, but it was still pretty muggy in the trees.
Another bit of advice – go early. This trail seems to be comparable to the Grouse Grind in terms of its draw for fitness buffs, and as such it gets very crowded by midday. We saw a lot of people coming up the start of the trail as we were coming down, but were fortunate to practically have the trail to ourselves for much of the way up.
Also, dogs are allowed on the trail, but for most of it are supposed to be on leash, and there was a ranger who passed us who reminded us of this fact.
All-in-all an excellent hike for both enjoyment of nature as well as an opportunity to stretch the legs and get a good workout. Highly recommended.