The cardboard app works fine. I'm just wondering if I'll still get the full immersion effect with my screen size. Was looking at getting the homido
Definitely try a cheap one first, like Jerry posted above. However, I've used cardboard on my iPhone 5 (which is a 4-inch screen) and it worked OK... The screen will literally be inches from your face.
I have noticed though that the whole "immersion" thing and how well you like VR in general varies from person to person. Some people love it, others feel it's a gimmick and aren't that impressed. With units as cheap as what Jerry has found above, I'd try it for myself and see.
Just my .02....