I haven't stayed there, but it's in a nice location to access Hetch Hetchy. The hike to Wapama Fall flowing into the reservoir is nice, tho' the bridge across the creek isn't yet repaired.
You'll be about 45 minutes from Yosemite Valley. If Tioga Road is open, you'll be well located to access the high country. Perhaps the road will be open far enough that you can do the May Lake hike or continue up to Mt Hoffman. You'll definitely be able to hike into Tuolumne Grove of Giant Sequoias.
It's a bit further to Glacier Point, probably at least 1.5 hours.
Here is the Park map: http://www.nps.gov/yose/planyourvisit/upload/YOSEpark2003.pdf You can see the tent symbol on Evergreen Road just outside the Big Oak Flat Entrance; I think that's Dimond O.
I put "Dimond O" in the forum Search In bar and found a relevant conversation from 2008: http://www.tripadvisor.com/ShowTopic-g61000-i315-k1990245-Diamond_O_outside_the_park-Yosemite_National_Park_California.html Hopefully the bear boxes have been replaced or repaired.