The Mist trail is a beautiful hike that is a must do. Unfortunately, for the same reason, it is super touristy and crowded (esp on long weekends). I would recommend doing on a long weekend or weekday if possible -- although it starts to really feel like you're hiking in nature, once you go past vernal fall and start heading towards the top of Nevada fall (harder hike== less people!).
True to its name, the trail takes you through two waterfalls (if you go all the way to the top of Nevada fall) and there is a constant "misty" spray of water throughout, so prepare for getting at least a little wet!. The total hike time for me, from trailhead to top of Nevada falls via Mist trail and back via John Muir trail, took about 3hrs... but, then I did to a "trail run" down John Muir, so the descent was just 45 mins!!
Vernal Fall...
Trail signs while you get close to the top of Nevada Fall (on my next trip, I hope to backpack through Clouds Rest and get to the base of half dome so I can avoid all the "touristy" crowd and also explore the backcountry!)
Stream on top of Nevada Fall (above the fall)...
Nevada Fall Gushing down...
View of Yosemite Valley from the top of Nevada Fall...
View of Nevada Fall about 1/2mi out as you start to descend via John Muir trail (don't forget to look back and you walk!!)