This is definitely worth the money, as it kills pimples very quickly without having to deal with the annoying affects of gels and whatnot that can dry out your skin or irritate it.
I did read somewhere though that you have to be careful not to push the "on" button to turn it off because it shuts off automatically and that will switch it back on and start a new cycle, so that was good to remember.
Usually, it helps to pop the pimple first because I noticed it disappears a lot sooner if you can get some of the stuff out BEFORE using the Zeno as opposed to after.
If I have a really intense, deep pimple, I'll hold it on for the full 2 1/2 minutes, but if it's not TOO serious, I'll switch it to another pimple halfway through the time to conserve the cycles, which seems to be working out. After that, I usually put a dab of a clay mask on the pimple and it'll usually be gone by the morning.