I love my Nook too, and for the most part it's pretty stable, but I've had alot of annoying little problems with it too. I've had mine since around the end of January.

One of the biggest problems with mine is the OS is a bit unstable when it comes to reading books you sideload (copy onto it yourself). If you copy a bunch of books onto it, and it somehow doesn't like just one of them, you can be prevented from even seeing your entire library (of the one's not downloaded directly from B&N). You'll go to check for new content and it'll just hang there forever. You need to go back and slowly delete everything you just put on until you discover the one it's gettign hung up on, which can be a big PITA.

If B&N could at least just add something to it's error checking to put a dialog box on the screen telling exactly which book it's choking on, it would help immensely. Either way, B&N does put out nice updates and frequently, so here's to hoping they get that little problem worked out real soon.