I have used 10S exclusively for a few years now, and I really like it for a number of reasons. Also I "Less than like" it for a few reasons.
What I like about it:
*It pairs well with other rider's Sena headsets, as well as the older models. It came pre-paired with it's sister unit (bought as a set)
*Helmet to Helmet communication is very clear, and it does an amazing job of cancelling out background noise.
*It works well paired with my iphone. I can control music, activate Siri via voice-commands, send texts, make/received calls, have texts read to me as well as Nav-directions, all controlled by the Sena headset. I don't have to touch or even look at my phone during use.
*Battery life seems exceptional. Will easily last a 10-12 hour marathon day of riding, talking, and listening to music. 13-hours is about its limit.
You can extend this as long as you need to with a little USB pocket-battery-bank.
*The headset allows you to plug in your own set of earbuds if you prefer using those, instead of the supplied speakers.
*It easily un-clips from the helmet-mount base, and they sell the helmet mount separately. This makes it extremely easy to switch one headset between multiple helmets.
*It charges very quickly.........It will fully re-charge from near-dead in a little over an hour.
*It is fairly "Water resistant" within reason. I have ridden with it in rain on a number of occasions.
*You can "Share" music from your bluetooth source with another paired Sena headset (but only if it is the person riding pillion) any further away from your helmet than that and this option becomes "Glitchy"
What I dislike about it:
*Helmet to Helmet communication range is not what they claim. "Line of sight" is good for about a 1/3-1/2 mile. If you lose line-of-sight, like over a rise or around a bend, or through trees then the range is good for about 50-100-yards at best.
*If you pair any more than 2 of these at the same time, the system defaults to "Open-Mic" on all of them, and you hear every sound broadcast from everyone in the group, all the time..................maybe the new "Mesh" technology ones are better at this?
*The sound from the speakers that are included is rather "Tinny". I listen to music often, and the sound they produce is not very rich........
I am not so sure it's the speaker's fault as much as the sound drivers within the electronics of the headset itself? I did try an experiment where I switched out the supplied speakers with a set of Skull-Candy drop-in speakers (which sound amazing in my ski-helmet when connected to my ipod) and it made those sound just as tinny?
*It is not "Water-proof". If you ride in extremely heavy rain, you will have to take precautions to make sure water does not work its way into the connection between the unit and its mount-base. There is a rubber gasket there, but it will deteriorate if you frequently remove/reinstall the unit to the base. Make absolutely sure you never try to submerge it!
*There were a couple bugs with it at first, mainly with its integration with my iphone. Although, subsequent firmware updates released from Sena have fixed them.
Hopefully this gives you some helpful info....