I used my skip dots on my desk at home and work for a while when I first got the phone. They worked fine. I could just set the phone on the skip dot and it would stay unlocked. I've since installed the "Delayed Lock" app with the wifi add-on and now my phone just stays unlocked on my home and work wifi networks so I don't need the skip.
I stuck a dot on the dashboard of the car so I could just tap it to unlock while driving. Going a step further, tried sticking the skip dot on my cell phone holder in my car so it would continually contact the back of the phone so the phone would stay unlocked while I was driving. But it didn't seem to work right when the car was in "driving mode" on the Moto Assist app. I can't explain, but it seemed to re-set the skip dot so it wouldn't work, and I'd have to reprogram it. I never really looked at the problem or tried to figure out exactly what was going on though. So I don't know if that was a real problem, idiosyncratic, user error or what. I might mess with that a little because that would be a handy feature. I do like the driving mode so won't disable that except maybe to try the dot again.
I tried to use the magnetic thing once or twice, but my cell phone usage on the go isn't high enough to warrant fussing with remembering to put a gizmo on every morning and keeping track of it Hell I dress very casually, don't even shave or wear a watch, so I'm not one who does much of anything to "get ready" in the morning and the magnetic skip would be totally incongruous with my lifestyle!
Conclusion: the things work just as advertised, and if you have a situation where they'd be handy, they will be.