I tried it last week on my Galaxy S6 Edge and it worked really nice. Tried a Rollercoaster app, Sisters, Divergent VR, Insidious 3 VR and Orbulus. They were all fun (Twins and Insidious are pretty scary lol) but it is a novelty and something to show friends when they come round.
I paid £2 for the google cardboard from ebay and I haven't messed with it since. It's worth the try if you have a good phone though imo.
I can't see myself spending any real time with it now but if anyone knows of any other good apps to use with it please post them!