IT's easy to use, and seems effective so far. Just plug it in and wait for bugs to zap themselves.
Only 4 stars not 5, b/c it has a fairly short power cord, and no on/off switch for main device (only for the LED light on bottom) so you need to keep plugging/unplugging when you want to use it.
Otherwise it seems to work well. Over a few days, I've only zapped a few houseflies with it so far, but it goes from a fly zipping around the house, to eventually finding its way to the zapper, hear a small snap, then things get quiet again.