Not the format, but the reader, 95% of the time...
Also... a vast number of user complaints about PDF have nothing to do with the format or even how they are created, but with craptastic knock-off variant readers that don't hew to the Adobe standard. Adobe Reader is free, in several variants for nearly every active platform; there is no reason to use any of the third party knockoffs or, for crikey's sake, the crap built into most current browsers. They are for reading only the simplest, least-feature-rich forms of PDF and break on every little detail.
So I find it hilarious on top of my prior comment that someone bitching so bitterly about the format thinks a new viewer in Firefox (which I fiercely adore, by the way) is The Solution.
It's not. Using the real Adobe Reader is.