This is a bad detector, but for $30 it may indeed save you once or twice. It's certainly better than nothing.
The best ones cost $300-$400 (Escort 8500 - Valentine One).
But you can get very similar preformance out of Bel models (like the 910 which is only $85 new at several online vendors). This is what I'm looking to buy, it is just as sensitive as their top models (almost identical sensitivity compared to the Escort and Valentine one) but has fewer features (like "voice alerts" or ideitification of the exact frequency of the radar (still tells you which band, Ka, X, K, Laser, etc).
Most people who are really into radar stuff suggest nothing but the best, but I think for about $100 or even less you can get almost the same preformance from a Bel detector.
The Whistler 1783/1793 and PNI Sensoro 7500/7600 and Travler II are also good solutions for slighly less (like $70-100). The PNI model is cordless (slightly less sensitivity but no cord over your dash, still better than this detector by leaps and bounds).
I had a cheap PNI 5000 from Buy.com (price mistake of the day) and it saved me twice. But it missed a few traps.
Someone said that avoiding tickets is about 90% awareness and 10% detector, that sounds about right. Also, this detector does not have VG-2 invisibility (meaning some cops will be able to tell that you're using a detector, though it's kinda rare).
I'd say save up a bit and get something that will help a lot more, but don't blow your money away on a $300 or $400 detector unless you really need some electronic voice to tell you to slow the he!! down or really need to know the direction from which the radar is coming from.
Just my $0.02,
Serval