The trouble with .pages files
Pages is Apple's word processor on Mac, iPhone and iPad. Its .pages files cannot be opened in Microsoft Word, Google Docs or on Windows and Android, so people often receive a file they simply cannot read.
What this tool really does
A .pages file is a package that usually contains a ready-made preview of the document. This tool looks inside and takes out the embedded PDF preview if there is one; if there is only a picture preview, it turns that picture into a one-page A4 PDF. It is honest about this: it is not a full conversion of the Pages document, and the preview may not include every page.
When the result is complete — and when it is not
Documents saved by recent Pages versions often contain a preview PDF of the full document, which gives a complete result. Older files, files saved with “include preview” turned off, and very long documents may contain only the first page or a small picture.
Common problems and how to fix them
Only one page appears: the file contains only a first-page preview — ask the sender to export it from Pages with File → Export To → PDF or Word. “No embedded preview”: the file was saved without one. The preview is blurry: it was a small thumbnail picture, not a full document.
Good habits
Ask Mac and iPhone users to send PDF or Word files for important documents, compare the result with the sender if anything looks incomplete, and keep the original .pages file.