Originally Posted by DSpider
There was a study that showed that 8 or 9 (out of 10) people do not bother with endnotes when reading a book, but almost all will read them if they're on the same page.
Which doesn't mean they appreciate having reading them
Sometimes footnotes have "useless" information for the casual reader, such as bibliographic references, a plant's scientific name, or a simple "sic". It is, however, hard to restraint oneself from looking at the bottom of the page to see what the footnote says, especially when other footnotes are interesting.
In general, I agree that more useful footnotes (e.g. those providing translation of foreing phrases) should be kept in page, and other more scholarly (and often longer) ones are better moved elsewhere.
In ebooks, however, where it is currently not possible to have proper footnotes, I prefer to have all of them at the end. Adding shorter footnotes inline in brackets or after the paragraph is, in my opinion, not a very good idea, at least not in narrative works, since they disrupt the normal reading experience. In more technical or reference works they are probably OK.
In any case, it's important to use appropriate markup, so they can be easily converted if/when needed.