It also needs a little LED next to the camera like on MacBooks etc so people you're talking to know if you're recording. A simple feature that would increase comfort amongst those around you.
Once economies of scale on the display kick in, the hardware can be fundamentally made significantly cheaper than a smartphone, everything and slower (vastly less CPU and GPU requirements as the software exists today, compared to a modern smartphone, although that could change if they start doing augmented reality stuff), it has fewer radios, less patent and compliance tax, and similar size/thickness/density/complexity. I think a $100 cost price should be easily achievable once the volume gets up. (I design hardware professionally.)
I assume this is for the eventual productised version and not for the current public beta / "explorer" version. I'd need at least a solid 24 hours of battery life with typical use, and some degree of weather resistance before I'd buy.
Visual design is a key, integral part of "look and feel" and usability. I would argue that even if you ask your users and they tell you they don't care about the aesthetics, they actually are influenced at some level by them. People (including me) are more likely to continue to use and contribute to a well-designed and attractive site.
I'm using Vienna (OS X) which as far as I can tell works perfectly for every one of the other 200+ feeds I subscribe to - but not for Hacker News. It looks like simply replacing the <comments> tag with a description tag containing (only) a hyperlink to the comments page would fix the problem. Many readers ignore the <comments> tag.