I have both a Note8 and Dex that I've been using for over a week on a long international business trip. I took a bit of a risk by deciding to just bring the Note8 as my sole computing device only after a day of using it at home.
As far as Dex goes, first of all, I love the vision and the concept. The execution leaves a lot to be desired, but since it is a first gen device, I'm hoping for some massive improvements.
For some background, I'm mostly in engineering management, so most of my workflow revolves around email and MS Office (the Word,Office,PowerPoint,OneNote quad). I unfortunately no longer get to do the cool stuff like coding and data analysis. Given my needs, you'd think Dex would be perfect. The biggest problem I have with the Dex experience is that the multi window feature doesn't do exactly what I expected. For instance, there is no clipboard. If I wanted to paste a picture from the web to my PowerPoint slide, you can't drag and drop. You save the pic into your phone gallery and then import that pic into your slide. There is also no way I could find to run multiple instances of something like Word either. So, with both issues, it lessens the need for me to have the Dex multi window environment.
The other issue I have with Dex is the size of it. When I opened the box I was disappointed with it right away. I was expecting it to be the size of a hockey puck, but it's more like a smoke alarm size to me. It's also got a bit of weight to it, presumably to give it a steady base to hold your phone safely upright on your desk.
I'll preface this to say that I'm an extreme one bag lightweight traveller and lugging the Dex dock annoys me because it is heavy and not useful to me. I also brought along a Miracast dongle and I find myself using that more than the Dex dock. There are other small reasons I prefer the Miracast, but this will be TLDR. And if I really needed a true multi window experience, I'd still use Chrome RDP in Miracast to get by.
So Dex could get there with some software changes. I can also confirm that Dex will not open with an off the shelf HDMI adapter. It seems like Dex was made for a workdesk environment. I hope they would make a travel version someday and do away with the Ethernet, USB ports, and weighted base. My ideal would be something like a external battery case sleeve, just a lone HDMI port, that has the cooling fan, and could double as a vent attachable car holder.
Anyway, typing this post in Dex right now with a Bluetooth keyboard that I hope to replace with a TB eventually. Obviously I want it for lightweight travel, but reading these TREG reports it sounds like there is a far greater vision for it, so I guess we wait with anticipation until they are satisfied with the execution.