The Samsung DeX is currently positioned as a mobile workforce productivity accessory for Galaxy S8/S8+ users. By slipping their phones into the DeX, a unique Android desktop mode is enabled that allows users to take advantage of a larger workspace with movable and resizable apps, USB keyboard and mouse input, and USB storage support. Overall, the DeX experience is impressive though I have to say that at least as of May 2017, it doesn't quite seem ready for prime time. Early adopters and tech savvy users will have a lot of fun with it, but I'd be cautious about recommending DeX to the masses at this point in time.
 
With that said, I fully expect that the DeX experience will only get better since a lot of the Free-Form Multi-Window functionality that comprises the desktop experience is actually built into Android and isn't proprietary Samsung wizardry. There are Samsung specific UI elements and integration of Samsung hardware features not native to Android, but at least according to the Samsung DeX Developer documentation, the only thing app writers need to do to take advantage of DeX's capabilities is to make sure their apps utilize Android API 24 or above and comply to the Android N Multi-Window standards. Although it's reserved as a premium feature today, I figure that within the next two to three years, the ability to use any mainstream phone as a basic desktop will become a standard feature and that some derivative of Android will emerge as a good-enough desktop operating system alternative for a significant number of users.
 
I used the DeX with a Galaxy S8+ for about a week before writing this review and found that while not everything runs in DeX mode (Spotify and Kindle don't run at all), many apps are able to launch though only a handful outside of Google's offerings support fully resizable windows at the moment. Most apps (including Netflix) launched in a fixed mobile view and depending on the app, there might be an option to choose between portrait and landscape views. It's worth noting that while an app might launch in DeX mode, there's a chance it might require touch controls and thus be unusable (e.g. Super Mario Run). I'm hopeful that many of these issues will be sorted out in due time as app writers update their apps for future versions of Android.
 
Beyond specific app compatibility with DeX, the majority of issues I encountered can be lumped as either multi-tasking/focus related or inconsistent behavior issues that stem from either limitations of specific apps or Android itself. An example of a multi-tasking/focus problem is that the majority of non-resizable apps stop refreshing when they're in the background; while having carefully controlled background refresh is desirable on power-constrained systems that only allow one active app at a time, it's lame when a CPU utilization monitor app stops updating when you switch apps. An example of an Android or app specific limitation is that not everything understands the mouse wheel; while the mouse wheel works as expected when using a browser or Microsoft Office, some apps like Google Drive's PDF Viewer require you to scroll by clicking and dragging. Gmail is a curious offender because it’s resizable and supports multiple panes, but it only does so when it's expanded to nearly 75% of the desktop. As with app compatibility, I am also hopeful that these issues will be ironed out in time, though it might take longer if the fixes require tinkering with Android.

In terms of hardware, it's interesting to note that the DeX actually works as a generic USB-C phone dock, and it will allow any phone to display, charge, and use USB devices as long as the phone supports USB Power Delivery and DisplayPort Alternate Mode. Imagine my surprise when I hooked up a Lumia 950 and watched it seamless launch into Windows Continuum mode with USB keyboard and mouse support while also being charged! My friend was also impressed (albeit to a lesser degree) when his HTC 10 went into Display Mirroring mode, a mouse pointer appeared on his home screen, and a message confirmed that the phone was also indeed charging. The DeX ships with a Samsung charger it also worked with both universal USB PD chargers that I tried, but it did not work with either a Qualcomm QC 2.0 or standard (Non-PD) 15W USB-C charger. It's unfortunate that DeX doesn't work with standard USB-C chargers since the 15W variety actually provides the same amount of power as Samsung's own AFC charger. I hope that other manufacturers are taking notes...if every product were implemented in a standards-based way, we could simplify the buying experience, improve consumer satisfaction, and reduce waste! What a concept.
 
Ever since Ubuntu unveiled its Edge concept in 2013 and USB-C was developed to support a single cable/connector for simultaneous power, video, and data transfer, I've been looking forward to having a single device that could seamlessly provide a unified mobile and desktop experience. Microsoft's Continuum was an awesome idea and it's a shame to see Windows Phone in such a state. Looking at the DeX hardware, it's interesting to note that it's good enough already (adding a 3.5mm audio jack for headphones/microphone would be appreciated though). The only thing we need now is for the software to catch up, though I'm hopeful that the phone docking concept will go mainstream within the next two to three years. All things considered, I think bringing DeX to market now is a bold move and Samsung deserves praise for doing so.
 
Notes:
1. While the DeX works as a universal USB-C Dock, the S8/S8+ requires the DeX to go into DeX Mode. It will go into screen mirroring mode if you use the Microsoft Display Dock or a generic USB-C to HDMI dongle. If using Bluetooth input devices, you'll need to pair in phone mode before using DeX because DeX requires at least a mouse to be connected.
2. You'll need an Office 365 subscription to use the Microsoft Office suite, and you need to keep in mind that you're still getting the mobile version. All of the apps have full reader functionality but limited editing capability when compared to their full-powered counterparts. You can show PowerPoint presentations and see transitions and animations, for example, but you don't get the presenter view (since the S8 screen is off in DeX mode) and the entire animations tab is missing even though you can add slide transitions.
3. You'll probably need to remove your phone case to get it to work

I'm just posting this review to counter the negative review. I ordered the DeX station for my new Galaxy S8+. I carefully researched it before buying. It appears to have just what I need. I like the idea of the cooling fan. Good feature. And, I am impressed that it has 2 USB regular ports and one USP-C. Plus it has HDMI port.
Being an older person (70 years old), I'm looking forward to using the DeX to help me to use certain phone apps on a bigger screen, with the use of a mouse and keyboard. I just have a feeling it will be a big help to people who are disabled or elderly.
Even though I'm on a fixed income, I'm willing to pay the $149. for it to finally be able to use phone features I currently have difficulty with. I feel I will finally be able to really enjoy my smart phone to the fullest. Thank you Samsung for making this neat little contraption!

I don't know why my review doesn't say 'verified purchase' but I did buy the DeX here on Amazon.

The Good: Overall, I think this is a good first attempt at providing a Microsoft continuum experience to Android. It has some minor flaws that I'm willing to overlook for the sake of innovation. I'm hoping they provide improved app support and more refinement over time.

The Bad: the mounting of the phone without the case is tricky. It just doesn't engage smoothly. The mounting of the phone WITH a case is nearly impossible. They did make the usb-c connector movable, but haven't been able to mount with medium bulk UAG case. It really annoying to remove case every time. How many people are going to buy a $950 phone and not put a case on it. I think I am going to buy usb-c extender and forego the dock entirely.

The Ugly: overall cheap plasticky look and feel of the device. Now where near matches the fit and finish of the phone. It just looks and feels cheap.

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Update 9/18 - I purchased a USB-C 3.1 Male To Female Extension Cable (see picture) to overcome the case versus docking issue. Works great and charges phone. I can now continue to use the cameras, headphone jack, etc.