I'm all for catching mobile phone users, testers and the like - and also people who speed where it really is dangerous (near schools and in built up ares).
But, most non urban speed limits today are way too low for optimum safety (I say this after having worked many years ago, on designing road and white lining schemes, which used to based on science rather than the now popular "slower is safer" approach) - so I'm totally against out-of-town cameras and especially camera vans on rural dual carriageways and "open" roads.