See
this thread.
The G-plus is a thicker (12mil) single-ply head. Because it is thicker it has greater sustain than the G1, which is thinner, and considerably more than a G2, which is 2-ply.
Durability has more to do with stick angles, tip shape, and the relative sanity of the drummer than the thickness or number of plies. My kid is the hardest hitter I've ever heard (no sh!t) and he
never dents his single-ply heads. Ever.
They sound nice, about you would expect from a thicker G1: a bit fatter, denser, more sustain. I've actually been using a couple as resos on my kid's kit. With the tuning we have on his 8-10-12-14f-16f the 8 and 10 didn't sustain as long as the other drums. With the G-plus resos they match up much better. If you have a drum that at its preferred tuning doesn't match the sustain of your other drums, this is a great way to even things up.
Be advised that the "coated" version of the G-plus is the Evans frosty "coating," not a real sprayed-on coating. To my ear the Evans frosty finish sounds like ass, more plasticky attack and no useful improvement in tone. Ugh. Stick with clears.
If Evans ever offered the G-plus with a real coating I'd be all over them as batters.