- The specification is more than 1300 pages long.
- The first version is 10 years old.
- Adobe has his own specification to “extend” the existent one.
- Adobe is not the only one that “extends” pdf specification.
- PDF can embed javascript, with a custom standard library full of crazy features.
- PDF can be scripted via a subset of PostScript
- PDF can embed Flash
- PDF can embed 3D objects (because why not?).
- PDF can embed virtually any data that you want, even video!
- PDF can/may be compressed, or not.
- PDF can do some kind of ghetto-versionning
- The PDF format is a piece of shit.