The Dying Earth is one of those classics I knew I should get around to reading. I absolutely adored Vance's Lyonesse books, and I thought I would like this as well.
At which point the best I can say is "meh, maybe not so much." The books are solid. Vance's writing is still solid, his magical systems interesting, his writing is very flowery and silly and intelligent and interesting, but it wasn't as interesting (to me) as the Lyonesse series. He rushes from idea to idea, scene to scene is some sort of wild abandon that almost doesn't make sense, but does string together.
I think it was still a good, solid read, and I would recommend any person who is into reading fantasy get to this at some point. It's important, and you can look back and see the influence this has had on other writers and works. Important - absolutely, a great read? Not for me.