Absolutely amazing! We stopped here for an afternoon and camped during a 10-day road trip through the West, and this was definitely one of the highlights.
I'd recommend staying at Jumbo Rocks campground - the name says it all. There's tons of large rocks that create small alcoves for each campsite, so it feels pretty private. Plus, you can go climb around on all the rocks for a few different views. We explored a few trails during the afternoon and each sight was cooler than the last - you'll definitely feel like you're in another world. The yucca trees against the rocks and the sparse desert landscape are unreal.
But the best part is easily the night sky - I have never seen anything so spectacular. You feel as if you could reach out an touch the milky way as it appears so close and bright. And as a woman at the local grocery store told us, make sure to keep an out for those UFOs!
It's a great national park, and I can't wait to come back a spend some more time there!