It's an interesting and fun stop on your way in or out of Vegas. It's about 5 miles either direction off the freeway, but pretty easy to get to.
They've caught my attention a few times driving by, so it was a natural urge to go see it for myself. Unfortunately if you're not here early you may miss it, as the surrounding mountains makes it about an hour early darker here than sunset; at least in the fall.
Overall it's just a bunch of colored rocks in the dessert. It's interesting, a little fun. Stop if you've got the spare time. Heard they will only be here for another year or two.