I've owned a pair of gunnar glasses for a year or so now.
When i first got them i didn't really notice a difference apart from the screen being more yellowish, after a few days how ever i noticed a lot less eye strain and i stopped noticing the screen being so yellow.
Lately i haven't been using them much for gaming as they kind of annoy me when i have headphones on even with their slim wraps.
What i still use them for is reading and browsing the net.
One thing to remember is that everyone's eyes are different so you may or may not notice anything.