The hike in is not to be taken lightly but the trail is as good of an example of ancient Hawaiian road (trail) construction over otherwise inaccessible terrain as you can get.
Once you are in the valley, it's a magical place filled with a remote kind of magic you can't find many places.
My only complaint is the constant parade of helicopters flying through the valley but I suppose that's the only way most people can experience this place of beauty.
Add this one to your bucket list. In terms of hikes and camping in Hawaii, it's second only to Kalalau.