Opinions? Now that it has some support for Linux I personally no longer have any real reservations if RWS choose to use it in whatever their next game project is going to be.
Unreal Engine 4 subscription enables you to deploy to Windows PC, Mac, iOS and Android. This is all available through the engine and tools download from this website. If you access the source code, you'll see that there is early work on other platforms, including Oculus VR, HTML5 and Linux. You are welcome to extend and modify this code, and also build and ship games for these platforms.