Mainly that's because the camera -- available for $350 in the US and £350 and AU$500 in the UK and Australia -- is currently only officially supported for use with Samsung Galaxy S6/S7, S6/S7 Edge, S6 Edge+ and Note 5 phones for use with the Samsung Gear 360 Manager app. That cuts a lot of other Android and all iOS users out.
On top of that, the bundled editing software called Gear 360 Action Director made by Cyberlink is Windows-only. This wouldn't be so bad if there were more consumer-level editing options for 360 content available, but there aren't. The bigger issue, though, is that you need either one of those Galaxy phones or the Cyberlink software to easily convert what the camera records from its two separate cameras into an equirectangular view (think flattened sphere) that can be edited and uploaded to YouTube and Facebook.
Basically, if you're considering the Gear 360 because you want a simple way to capture, edit and share 360-degree video and photos, you better have at least one of the aforementioned Galaxy devices and maybe a reasonably powerful Windows PC, too. You can still use the camera on its own without connecting to its mobile app and do the stitching and editing with other software (here's how to do it using Kolor Autopano Video software, for example), but it is much more difficult and time-consuming.
The camera itself is pretty straightforward to use. With the three buttons on the camera and its small screen you're able change basic settings and shooting modes, of which there are four: Video, Photo, Time-lapse Video and Looping Video. Switch to the mode you want, press the record button on top and the camera does the rest, simultaneously capturing the view from the front and rear cameras and combining them into one MP4 video or JPEG photo. (You can also shoot with just one of the cameras giving you a regular wide-angle video at resolutions up to 2,560x1,440 at 30 frames per second.)
Want more control? Wirelessly connect the camera to a Galaxy device, open the Gear 360 app and you get a preview of your shot as well as sharpness, white balance, HDR, exposure, ISO limit and wind cut settings. You can also turn on a 2-, 5- or 10-second timer.
When you're done, you can view and transfer content straight to your Galaxy phone and as that happens it will stitch together the views from the two cameras into photos and videos that will give you the full 360-degree spherical experience. Keep in mind, though, the longer the clip, the longer the transfer takes, so it's best to keep your videos short.