YI has continued to issue firmware updates for the camera, too, improving performance and adding shooting options. This includes a flat color setting for easier color adjustments when editing and an "Ultra" resolution setting that, like GoPro's SuperView setting, takes a 4:3 aspect ratio video and digitally stretches it to 16:9 to get more of a scene top to bottom in your shot. The complete list of capabilities is extensive to say the least and is available on YI's site.
Unfortunately, what it doesn't correct for is the amount of chromatic aberration (purple fringing) around high-contrast subjects, such as the buildings against the sky in the above video. In general, you probably won't see it when squeezed down for viewing on a smartphone or tablet. But blown up on a computer screen it's easy to see. Also, like most small-sensor cameras, highlights can easily be blown out, costing you details in bright scenes.
Once you're done shooting, you can connect to your smartphone using the camera's high-speed Wi-Fi and YI's mobile app to view your clips or photos, transfer and edit them. The built-in video editor lets you quickly cut a clip down, add a color filter or some text and export it out for sharing. Some of the app is still in Chinese, but you can pretty much guess what things do.
The camera also has Bluetooth for use with a small two-button remote shutter release that also lets you switch between capturing photos or video. You can buy the remote, camera and a really nice selfie stick for about $280. In fact, all the accessories -- whether you're talking about a microSD card for storage or waterproof housing or some other mount -- will cost you extra. For $250, you just get the camera, one battery and a Micro-USB cable for charging.
YI used a standard tripod mount on the bottom, so there's no shortage of mounts available for this camera. The mount is off-center, though, which might make putting it on a helmet a little awkward. The $40 waterproof housing -- get this one -- has a centered GoPro-compatible mount on it giving you easy access to using those, too.
Overall, I like the design of the camera, even if it is somewhat generic, and the touchscreen is very responsive, so you won't have any problems swiping and tapping your way through the interface. There are recording lights on top and in front, but in daylight they can be tough to see and if you're staring at the screen, you'll probably find yourself triple-checking to see if you're rolling. Also, YI says the screen is made with Gorilla Glass, but, speaking from experience, this does not make it indestructible. More difficult to scratch? Sure, but drop it and it could shatter.
The YI 4K is undeniably a good deal for an action cam. If your videos are destined for YouTube or Facebook and you want a camera that's as powerful as a GoPro Hero4 Black, but with a touchscreen and for nearly half the price, there's little reason not to consider it.