I am currently employed as a vr developer and started learning using my galaxy S6 and a Gear VR. You're not going to be able to learn many important aspects of

I am currently employed as a vr developer and started learning using my galaxy S6 and a Gear VR. You're not going to be able to learn many important aspects of building a true immersive vr experience because of the lack of real graphics horsepower and motion controls, but mobile vr is a good way to start learning and the experience of building something in code and seeing it in VR around you is really incredible. Daydream is a really solid platform and there's absolutely a space to develop just for mobile vr, but even if you are only interested in "real" vr mobile is a great low budget way to get your feet wet.