I got an HTC 10 three days ago. This is the best phone I ever had. The build quality, the Sense UI and the BoomSound speakers are amazing. I had a Nexus 6P before, a great phone too.
The problem with HTC is that the differences between flagships are really subtle. If I didn't have the HTC 10, I would also be very happy with my Nexus 6P or a different flagship. The main differentiator of the HTC 10 simply does not really exist. It is a device that does everything very well, if not excellent.
For me, the HTC 10 has the best design, the best sound and the best UI of any other phone out there. The market is saturated and people only know about Samsung and Apple. Everybody else has a big problem, unless they start offering discounts.
Everybody says that HTC should offer the 10 at a lower price point. I do not think they can do that without sacrificing in features or build quality.