I'm not sure if it's worth the money for most, but I've been really enjoying mine so far.
The PDF reader works great for things like academic papers as long as moderately small fonts aren't a problem. Large PDF books don't work quite as well because links don't work on PDF in the current version. Some PDF slide decks work well, depending on the formatting - colored text on black background doesn't render well.
The built-in browser is OK. It's a nice novelty to be able to read wikipedia on this form factor of device.