The chaps over at PC Perspective have posted a review of the Western Digital's My Cloud EX4. Here's a taster:

Pros:

Compact, efficient, silent design
Highly flexible configuration interface
Extremely simple drive replacement
Great out of the box / setup experience


Cons:

Throughput speeds were less than stellar


Final Thoughts:


Overall, I am impressed with the Western Digital My Cloud EX4. As a storage product, it offers many storage options at a very reasonable cost, as well as a plethora of way to access that storage. USB devices and other networked targets can all be consolidated through the EX4's excellent interface and then easily accessed in a variety of methods and by a variety of mobile devices. Speeds were noted to be average for a typical consumer NAS device, but the strengths of the EX4 are clearly in the features and app capability.

The pile of features is great, but may be leading to complications as we saw some odd CPU bottlenecks while performing file transfers to and from the device, though we suspect those will be sorted out with future firmware updates. The Easy Slide system makes drive swaps as simple as humanly possible. Redundant power supply and ethernet failover capability are welcome additions, and while those are more expert-level features, it's good to see enterprise goodies trickle down into a consumer product.