I had a Bel.. something.. in my old 32 but it went west when the car was broken into. Before I bought the detector I called the cops to check they were legal. The reply was "As far as I'm aware, they are not illegal". He went on to say that he thought they were a waste of money because by the time they go off, you're busted. :-\
I had mixed experiences with it. For the most part, it would work well with multanovas and highway patrol on long straight stretches. But if they're pointing the laser right at you, or if the radar is just over the next hill or around the bend, you'd be pinged before it had a chance to go off.
It was also pretty fond of giving false alerts - auto-opening shop doors are frequently the cause. The signals from these are usually pretty weak however, so it's fairly easy to suss them out. Plus theyre always in the same place - you get to know them after a while.
If anything, having the detector made me more cautious on the road cuz it showed up just how much radar is out there.