I find there are situations where they save my ass and situations where they are useless. In towns where there are hills and turns everywhere and the cops use radar they work like a dream. The detector will go off and then about 10 seconds later you see the cop around the turn or the hill. Mine has saved me a ticket numerous time in town.
On the other hand they are garbage on the highway. Cops will be using lidar or aiming the radar gun at you by hand and by the time the thing goes off you're screwed cause they've already got you.
Bottom line mine was a 60 dollar cobra and it does what i need it to do. I know alot of my buddies who have 200+ dollar detectors that don't work any better than mine.
One last note dont turn you're music up too loud or else you'll never here it go off. That's how i've got all my tickets