Having read in the mouse trap reviews that this unit was far better, I decided to purchase one of them. It arrived promptly on a Thursday.
The batteries are a pain to install, as suggested elsewhere here, and the battery cover is a joke. I found that the best way to get the batteries in is to start with the spring end (-ve) ones first. They have to be pushed firmly to get them through the clips. Then put the base ends of the other batteries in so they rest against the top (+ve) end of the first ones and lever them in so they compress the spings and you can then get the top (+ve) cap down into the compartment!
I baited mine with a lump of bread roll as my mice had been ignoring peanut butter and cheese etc on my conventional traps for weeks! Placed against a wall where I knew they ran and a few crumbs trailed into the entrance to lead them in. Switch on and the green LED flashes briefly to show it's working. This was Thurs evening.
Fri morning, came down, periodic slow green flashing LED (about 10 secs between) 1 dead mouse, zapped against the end wall of it. Was in a rush, so emptied it out and dumped the unbaited unit back on the floor and switched it back on. Fri pm, another dead mouse, with no bait! Re-baited with bread roll, out on the beer! Sat lunchtime - 3 dead mice!! Re-baited, watched 1st Rugby international - another dead mouse! Re-baited again, watched 2nd Rugby international - yet another one! 7 in 2 days!! No more since then but no more signs of them either. The unit has been left switched on since then (now 2 1/2 weeks) and it appears to still be working fine on the same set of batteries. Very impressed!