Let's put it this way: you can see the Milky Way!
The skies are very clear and dark to the E, NE, SE, S, and SW. They're less dark to the West (duh) a Palm Springs is the big offender there, but on a clear night you can also see the skyglow over San Bernadino.
I think you'd really like it. All the camping areas feature wide open spaces where you can set up a chair and your telescope. Some of the areas are a bit more closed in than others, but you pretty much have your pick of where to set up. Ask at the Park HQ where the astronomers go and they'll point it out on a map.