I've had mine for a week, if anyone has any questions. I think the biggest downside is the lack of the headphone jack. I've tried this with various USB-C adapters and the phone won't work with anything. I always get an error message telling me that it only works with the original HTC headphones. This is completely nuts - they really have to start selling (or bundling) a USB-C headphone adapter that works.
It's a pity, because otherwise this is a fantastic device. Beautiful screen and build, blazingly fast. Battery life is decent as well, despite the relatively small battery. The camera is fantastic.
But without a headphone adapter available for it, nobody will buy it. I ended up shedding out another 300$ for Bose QC 35 headphones just so I can avoid the headphones that came with it. The latter are quite alright but I hated earbuds.