Colin Donnell:

Besides Finder, Evernote is the only app I know of that you can really just throw anything at — PDFs, images, text notes — everything. And it’s not just that you can put everything into it, it’s that it treats most of those things the same way (through OCR), so that doing a text search is going to bring up results from all of the above.

That is indeed one of my favorite aspects of Evernote (which, last month, was also updated to support search inside iWork and Office documents). The other, as Sean said, is saved searches.