Many of these stories were originally published in short story collections (The Same Door, Museums and Women, Problems) that are long out of print and difficult to find. That alone makes this worth owning. Then there is the fact that this represents the collected work of an indisputedly talented and influential writer coming strong out of the gate and finding his voice, at a remarkably young age, before settling into a career and a life.
It is fascinating to observe this evolution and growth, as it happens over two decades, as he moves from, say, "Friends from Philadelphia", which is literal and straightforward, to the Barthelmesque (I don't if that's a word, but it should be) "Problems", which is self-reverential and self-mocking, yet also darkly funny, hinting as it does at the way life has affected the artist and his work. There is the longer "Pigeon Feathers", the (very) short "Eclipse", and the effortlessly brilliant "How to Love America and Leave It at the Same Time". Not to mention the Maple stories (which I'd already read in their collected form in Too Far To Go), the classic "A&P", and about, oh, 80 or 90 others, not all of them gems, or even successes, but fascinating and worth reading nonetheless. Add to this the fact that you can observe, through Updike's writing, the country moving from Mid-Century domesticity to Sixties' upheaval and Seventies' rudderlessness and confusion, and you have a truly indispensable collection.
There is also the added bonus of Updike's introduction, in which he reveals his life at the time (married and a father early in his twenties), who escaped to an office to write during the day so he could support his family by selling these stories to the New Yorker. An unexpected, and unexpectedly normal, glimpse of the author and his workings, it's an insight which gives me a new appreciation for these stories and how and why they came to be.
Lastly, don't be daunted by the heft and bulk of this tome, and don't be afraid to pick and choose which stories you read, and in what order...they have a way of staying with you long after you're done reading them.