This is great! We were camping up around the lake district and it directed us to some superb little-used spots. It also has excellent suggestions for eating/drinking etc near each campsite and/or warnings if there's a bit of a walk. We definitely found a few gems (like the Drunken Duck!). It covers 40 campsites across England (each one gets a page or two, and some lovely photographs so you can see what you're getting) - not a huge amount of choice, but as it says itself it "features a hand-picked selection", and seemingly they visited hundreds of camp sites across England to find this list of 40, and i'd much prefer that to a huge list of ones where you turn up and are disappointed.
Something that i found a huge advantage, but that you might find a disadvantage is that they're NOT looking for "holiday park" type camp grounds - their (and my) idea of hell. so the ones listed here will be beautiful , or quirky, or in a brilliant location ... but they won't have lots of swimming pools and hi-de-hi activities etc.
The only (small) disadvantage is, although the directions to/from the campsites are detailed, it wasn't great with directions to some of the "nearby food/amenites" locations - but it does give phone numbers so you can ring and find out if you want to (i suppose it saved space).
Bottom line - i've just now discovered on Amazon (sorry - i originally bought cool camping : england in a little camping shop!) that there are companion guides to wales etc ... and I'm going straight out to put them in the shopping basket!