Some of the stories in this volume stand the test of time and remain brilliant. Others haven't aged well at all. And many are somewhere in between. But it's all a matter of personal taste. The standout stories for me were:
"The Star" by Arthur C. Clarke, which won in 1956; succinct and poignant, I remember reading this story before, in a college Science Fiction class sometime in the early 1990s.
"Flowers For Algernon" by Daniel Keyes, which won in 1960; I'd never read it before in any of its versions. Absolutely excellent, very moving.
I don't recall having ever read Jack Vance prior to cracking open this volume; both of his stories included here, "The Dragon Masters" (1963) and "The Last Castle" (1967) are absolutely wonderful, very evocative and alien. I'll need to look up more of his work.
I also don't recall having ever read Robert Silverberg before this volume; his 1969 winner "Nightwings" is excellent and beautiful. Another author I'll need to read more of.
It had been ages since I read any Anne McCaffrey and "Weyr Search" (1968) was absolutely delightful; I'd forgotten how much I enjoyed her Pern material at one point in my early reading career. I'll have to revisit those tales.
On the downside of things, I really got bogged down with Phillip Jose Farmer's 1968 winner "Riders of the Purple Wage"; I didn't care for it at all. I only recall reading, before this, Farmer's novel To Your Scattered Bodies Go, and I didn't care for that one either; I can't put my finger on it, but something about Farmer's writing doesn't click in my brain.
I discovered Harlan Ellison in junior high school (early 1980s) and for a long time I considered him to be one of my all-time favorite authors. I hadn't read much of his work in quite a while and interestingly, for me, each of his three stories contained in this volume, three of his most famous ones, fell flat for me on this reading. Apparently, as they do for readers, my outlook and tastes have changed.
Isaac Asimov's introductions were silly and not very informative and sadly some were tinged with sexism.
The rest of the stories in the volume didn't register very deeply. So they were OK but not great.
Overall, this time capsule of science-fiction award winners is worth reading. But for this reader, it does not need to be re-read, except for the few standout stories mentioned above.