Asciidoctor-web-pdf usually works, and when it does it provides much more flexible styling (through css) than asciidoctor-pdf (through rather limited themes).  However, there are several problems, generally related to non-text content that is larger than a page, such as long tables, or long source blocks, or images wider than the page.  These are bugs in the paged.js library that is used in the headless browser to prepare the document for rendering to pdf.  Paged.js is complicated, pretty much undocumented, and while not dead, not very actively maintained.  It does implement a standard, so there is also a chance that at some point browsers will support the  standard directly and it will become unnecessary.

I think everyone agrees that the asciidoctor-web-pdf approach is “the future” of pdf rendering, but it’s difficult to predict when it might become as reliable as asciidoctor-pdf.

FWIW I’ve adapted the asciidoctor-web-pdf approach to be an (experimental) Antora pipeline extension so you can render parts of your Antora site as pdf manuals.

David Jencks