This is a great run! The top is steep, but it's quite runnable.
From the parking area, dive right in to beautiful fir forest. You'll find mushroom, lush green undergrowth, and stream braiding everywhere. The surface is pretty rocky and rooty, and even though it's not too steep, it's not that easy.
After a mile or so, you'll use an old mining road for a short period. After that you start hugging the creek more closely, which forms fascinating rock clefts with waterfalls. Near the lake, you'll take a bunch of very short switchbacks and then pop out on a bench with Fancy Lake. Soak in the views and consider turning around here if you're tired or the weather is bad.
Continuing on though, continue up the trail up MUCH steeper terrain up above tree line. The last bit of this trail has a groove carved into the alpine rock. There is an old mining sled at the bottom; imagine hauling that up and down this crazy steep slope, at 12,000+ feet, even in winter!
From the top of the pass, you can connect to the Missouri Lakes Trail #2003
and make a big loop, or turn around here.
The fir forest here is unaffected (so far) from the pine beetle epidemic that's decimated other areas in Colorado. It's particularly nice forest.