Never been to that hostel, sorry.
If you want to use it as a base for touring California gold country, it's a good location. But be aware, if you want to use it as a base for Yosemite, well, Yosemite valley is a good hour away, down a twisty road. I wouldn't stay there if Yosemite were my aim.
Sorry, one of my pet peeves is all the hotels in the Mariposa and Midpines area advertising themselves as "gateway to Yosemite". Unsuspecting tourists don't realize that they have a hard drive ahead, every morning and every evening, if they're going to Yosemite.
-Bob