I am not saying that the book is without value. I'm in no position to evaluate the purely scientific arguments, so I'm looking forward to seeing what other specialists say about them, but the book certainly contained a lot of history and philosophy of science worth thinking about. So no, this wasn't a case of "painful because a waste of time."
The problem was Gould's writing style. Let me show you the passage—on page 10, no less—that made me set the book aside the first three times. What Gould wants to say here is, more or less, "I don't have to agree with other Darwinians about everything in order to count as a Darwinian myself." Here's how he decides to put it:
My allegiance to Darwinian theory, and my willingness to call myself a Darwinian biologist, must not depend on my subscription to all 95 articles that Martin Luther nailed to the Wittenburg church door in 1517; or to all 80 items in the Syllabus of Errors that Pio Nono (Pope Pius IX) proclaimed in 1864, including the "fallacy," so definitionally uncongenial to science, that "the Roman Pontiff can and should reconcile himself to and agree with progress, liberalism and modern civilization"; or to all 39 articles of the Church of England, adopted by Queen Elizabeth in 1571 as a replacement for Archbishop Thomas Cranmer's 42 articles of 1553. (Gould 2002: 9-10)
Reading the book means wading through over 1300 pages of this kind of thing. Great if one needs to reconstruct all of history after a nuclear apocalypse, and Gould's book is the only book that has survived; not so great if one is trying to learn about the structure of evolutionary theory.
In one footnote, Gould has the gall to jibe Herbert Spencer for "acute logorrhea" (Gould 2002: 197n). This puts him in the same company as the unfortunate Baron von Disputatio, who in 1614 declared in his Pater Mysterium that "alle confutation is itselfe no lesse than regicide most foule," only to find himself on the chopping block when his own heretical ruminations on Cornwallis's 13 Principles—spoken, he thought, in secret to then-ambassador Abu Ismail (he who Ignatius Lupus's 1625 Roster of Moorlike Personages styled "the one of laughing blue eyes")—came to light ten years later. By which I mean, he's one to talk.
Gould SJ. 2002. The Structure of Evolutionary Theory. Cambridge, MA: Belknap Press of Harvard University Press.