A few points:
At this price point, truly "waterproof" does seem far fetched. However, the unit is cased in a rubber skin, and I believe the only seam is the plate on the back, which doesn't seem like it should be difficult to seal. So, I would not be surprised if this is in fact waterproof up to everything short of maybe dropping it a bucket of water.
Although I believe both the technology, and components are similar to a Sena (or any other brands for that matter), it's obviously not a direct knock off. I have no experience with the Senas or any other brands, but the Sena has a dial, and this unit does not. I doubt the components used are the same quality as the name brands, including the internal components(chips, battery...etc.). ALL of this stuff, including Sena, is manufactured in China, most likely Taiwan. But, so is your iphone. As far as how it will perform in 6 months or a year, I suppose that is to be determined. For how often I now ride, and the fact I probably won't use this often, I would expect mine to last as long as the battery holds a charge.
I was also surprised by the GPS comment(s). I've never owned a GPS until I got my first smart phone about 5 years ago. I now have a Galaxy S6. I don't see how my S6 with Google Maps could be improved . It is perfect as far as I can tell. Not only has it gotten me where I've needed to go every single time, it also tells me, to the minute, when I will arrive. I see absolutely no reason to own a Garmin, in fact, I can't believe there is still a market for them.
This was never meant to imply this meets the same standards as Sena, or others. As I originally posted, I started out looking for something in my helmet to allow me to hear my GPS. Anything additional really is a bonus. If others have the same experience with this unit similar to mine, I don't see how anyone could complain about the features/performance to cost ratio. I got that helmet from Chaparral on closeout for $90. Add the $30 for the bluetooth and I think I have a hot set up for $120 all in. After about an hours work to modify the foam (long story), and install the BT unit, I have a helmet that fits perfect and had some decent BT features. Obviously I am not the guy that is going to spend anything in the $200 range for a Sena.
And they do follow up and fix them although the postage is on you. BTW does Garmin pay for return postage? I understand the price point well - for what a ZUMO of the day costs new, I can buy 3-5 Chinese GPS systems. And the ones I have are still working well unlike the rental ZUMO550 that died with a cradle failure. It appears to be the same with this unit - it's just a matter of how you want to spend the money. Good, bad or indifferent most electronics seem to be made in China and those manufacturers don't mind copying someone else's technology for sure! ;-) We live in a 'if it breaks, toss it' society now (my dad was a TV repairman at one point in the old days), so many companies are keen on the price point.
