I don't think jwz (who is much smarter than me) has many good things to say about OpenGL ES
http://www.jwz.org/blog/2012/06/i-have-ported-xscreensaver-t...
http://www.jwz.org/blog/2012/06/i-have-ported-xscreensaver-t...
In any case, I submit to the opinion of experts - my experiments with OpenGL have been simple and, when I attempted anything more complicated, they resulted in much more frustration than learning.
fixed that for you.