Word. I am not a huge fan of some of his signature films (Little Mermaid, Lion King), but looking at his actual art, I realize that its the stuff he didn't have anything to do with that makes them a mixed bag for me. His contributions are pure gold.
I recently took an online animation class offered by Mike Mattesi via his website (who worked at Disney in that time period), and in the first class, he highlighted Glen's work specifically as achieving the kind of movement and weight he wanted to get across to us in the work we did for class.
His work with Beast and Tarzan alone, I just kind of drop my jaw at. So marvelous that as an artist, it's the equivalent of a mic drop. This. Is. How. It's. Done. Full. Stop.