(Original post by mountainmetman)
It is around a months worth depending on how often you change the pages - I've got mine sat next to me and the charge last around that long if I don't leave the wifi on when it is not needed and have the text size small enough to fit a decent amount of text on each page.
With the wifi off the pages don't use any power (its a bistable thing) but after around 10 minutes it will go onto standby and change itself to a screen saver. Only real difference from the screen saver to normal use is the buttons are deactivated.
Mine has a dozen work/academic books/papers on it, pdfs are fine but you need to get used to zooming in and setting things to landscape to get the most out of it. That's my excuse for having it and the boss hasn't twigged yet...
Managing collections isn't as easy as it could be on the K4 and the Calibre system for collections isn't great but if you have good wifi connection leave everything in the cloud and just load what you want when you want it.
Word about Calibre, it's worth setting up the import options to strip the DRM from amazon .azw files when you import them, makes them a bit more open. If you want to try it there's a guide here