Right now, launching games to the Gear VR from UE4 need some refinement, and currently is not suitable. However, UE4 just introduced GearVR support a couple weeks ago and have been busy with a convention for one of those weeks; so, there is hope for better support in the coming weeks. The process of configuring the settings to launch a game for GearVR is actually not too difficult to get the FPS template to run smoothly. Unfortunately, getting ideal performance on the GearVR right now requires most of the graphic settings to be set low or disabled (like anti-aliasing), and things like dynamic/stationary lighting is a big no-no. For example:
MyGame’s Performance (actual game, not just a template):
Monitor: Maxed out FPS locked at 120 FPS (8ms)
Oculus DK2: Maxed out FPS locked at 75 FPS
Android Note 4: Maxed out FPS locked at 60 FPS
Note 4 in GearVR mode: 15 FPS with lower settings than the Note 4 non-GearVR mode
So, the fact that the Note 4 can run UE4 projects well without the GearVR enabled indicates that the potential is there, but the dev team just needs to tweak some things in the coming weeks. Given the quality and development speed of other VR support, it is safe to say that UE4 will be suitable for many types of GearVR games in the near future.