My understanding was that PDF-XChange Viewer Free wasn't simply a reader but also useful for annotating PDF-documents. My experience of such software is that is not free, and if it is free it comes with some kind of limitation so as to provide an incentive to get the non-free version. I am of the opinion that one should always try to exercise caution when something seems to be too good to be true. The reviews from snapfiles seems to be extremely positive, and that too triggers my critical mind, but I guess I will have to find out for myself now. If it does provide good annotation capabilities for free and with no limitations, then that is all that I need.
-jzippo
I've used PDF-XChange Viewer for about a year now and I've had no problems with it.
The annotation tools seem to work fine for me, though I don't use them all that much and don't tend to share the annotated documents so I'm not sure how well other readers will cope.