I actually just bought one (a 4GB pulse) in preparation for next semester. I've been playing around with it for a few days, though keeping it to a minimum to not waste the paper, and it seems pretty nifty.
Audio quality is okay, I have yet to see how it'll do in a lecture room though. Writing with it is a bit awkward for me, but I'm used to fountain pens so that might play a role.
I paid $140 for it, 4 binders, a leather case and a pack of ink replacements (eBay). And my first impression says it'll be worth it. Especially since I have several friends who've bought audio recorders for $80-$120. So paying an extra $20 for pdf capability and the rest seem like a very good deal.
I can let you know when next semester starts on how well it holds up.