I don't know about the rest of you, but I generally prefer to read real books, rather than online books.  In fact, I've commented before about how I only own one truly "digital book".  It was a book written by Dean Koontz, and at the time I bought it, it was only available online.  I have since bought a signed author's copy, and lost the online version.  But now I'm reviewing a new book on Microsoft Silverlight which is only available online in PDF format.

Most of the time when I use PDF's, it's for relatively brief documents that only amount to one or two pages.  I read the document, and then close it.  But now I'm trying to read a nearly 200 page online book, and I have no idea how to bookmark where I left off in Adobe Reader.  The author of the book can add their own bookmarks when they create the PDF, but how does a reader add a bookmark... like... where I left off?  Adobe Reader is in version 8 now, and either they still don't have this feature, or it's so hidden that I can't find it.  Shouldn't that have been in version 1.0?

I have a new book review posted on BlogCritics.  It's on Programming WPF by Chris Sells and Ian Griffiths.  This is probably one of the best technical books I've read since doing book reviews.  If you're interested in learning the latest framework for doing GUI programming in Windows, then this ought to be the book you buy.