If the Radar has the right features and the officer knows what he is doing, radar detectors are useless.
I had a guy pass me doing 45 in a 30 this morning. I'm in a big 'ole SUV that says "PO-LICE" in big letters on all sides. He didn't even tap his brakes or slow down. And he got butt hurt when he got a ticket. Oh well....... Who needs radar anyway??