Yeah, it's good. Well worth an afternoon's exploration if you're in the area.
Biggest problem is they removed (for obvious reasons no doubt) a lot of the most sensitive kit during decommissioning and replaced it with spares/generic stuff from other sites - the result being that some of the kit that's there shouldn't have been and some that isn't should.
As for the comparison with Cheyenne, that isn't really fair. The WWII bombs dropped on Hiroshima and Nagasaki were 13 and 21 kilotons respectively - nowhere near the megatonnage for which Cheyenne was intended to survive. I admit I'm not entirely convinced by the idea of placing water storage tanks on top of the Kelvedon site though.