I gave PDF Creator a go last week. It’s pretty good for a freebie, quite easy to use, and has some configuration and so on.
Trying it with Word documents it did seem to have problems with some fonts/styles though (generally for users other than me looking at the PDFs), so it’s worth being wary if you rely on accurate PDF-rendition. In my case, the (alas not free) Acrobat works better.
Ultimately I suspect for “industrial-strength” PDF-creation it’s best to stick to the genuine-but-expensive Acrobat Standard or Pro. The cheaper (or free) alternatives are pretty good, but don’t quite seem to cut it when the going gets tough.
Mind you if you’re not prepared to pay for Acrobat (AU$400+ for standard… pah, their time will come) I don’t see a compelling reason to get a cheaper one when PDF Creator is free.
Or if using Mac OSX, simply save as PDF from any application – no software necessary plus works better and faster than using a converter.