My wife and I use them and they work very good.....as advertised. It takes a little time getting everything paired. We each have our phones & Mp3 players paired to our individual helmets & of course the two headsets paired together. The only downer is that when you do a firmware update, you have to re-pair all the devices again.
They have very good range and the music is crystal clear. We use the one where you can plug in earbuds. Since we have full face helmets, we also use the microphone that sticks to the inside of the helmet. The boom mic works fine, but you have to make sure it's directly in front of your mouth or it's hard to hear the voice over the wind noise. When the mic is positioned correctly (whichever type you use) it picks up very well & is very clear even though there is some wind noise.
The controls are easy to use even with gloves on & the voice activation works as described. The latest update allows you to share music between headsets. In the past, each headset had to have its own music source, so it's one less device to deal with.
I haven't used any of the other systems so I can't compare. When I did my research a couple of years ago, it seemed that Sena had far more features and possibilities than the rest. I am very satisfied with it!