I've also used pagedjs for a relatively complex booklet with bidirectional text in different languages, images and long footnotes. The result was great but there were some annoying bugs, some of them seeming to be possible underlying bugs in chrome and Firefox. Still, latex would have been even more frustrating.
Coincidentally, I've also used pagedjs for a project recently (125K novel) and encountered some bugs/minor issues. Overall though, I would say I had an immensely positive experience (because even when stuff broke, it was still just HTML, CSS, and JS--so I, like any other web developer, could fix it).
That said, it's a shame that the relevant W3C specs (see https://pagedjs.org/about/) still aren't fully supported by browsers (but perhaps such is the fate of niche features), but with that being the case, I'm infinitely thankful that pagedjs exists as a polyfill.
Oh, I certainly don't doubt that. And as I said, I haven't really found Paged.js all that frustrating! I have extensive though not recent Pagemaker experience; I expected InDesign to be easier, and now I rue the day when that's where I'm forced to resort.
In my experience Paged.js is at its best when building to PDF, but then that's always my intermediate format when working to paper, because that's where PDF's inflexibility shines. The source of a book block, everything that builds to that PDF, partakes of all the infelicities of the JS ecosystem. But to remake the book itself again, all I need do to start is print the PDF.
