The Samsung Gear VR is great, but those who want to enjoy it would need a Samsung phone. The VR experience itself isn’t special technology wise, but Samsung does have one of the better headsets out there, and they do have various exclusive VR experiences.
It seems you might not have to have a Samsung device to enjoy that side of the tracks, though. One developer at XDA was able to get the Samsung Gear VR working with his LG V20. The process involves editing a build.prop file and adding all the prerequisite apps the Gear VR needs.
It’s not quite that simple right now, of course, with the developer only releasing his work intended for other developers to pre-bake it into their ROMs, but the eventual hope is that someone can make a flashable package to get the goods on any compatible phone and ROM with ease.
There may also be inherent restrictions, such as phones needing at least 1440p resolution and being able to actually fit inside the Gear VR headset. In any case, if you’re excited about what could be then follow the project in its early days at this XDA thread.