So I've seen this topic around for about a week now, and all the while I was thinking "My Kindle is like a nuclear bunker". Until today. I was outside reading, and I managed to drop it. "No biggie", I thought as I had dropped it, and even stepped on it several times. But, what happened this time was that it fell screen first on some pointy rocks. And that led to non-inverse-able damage. Basically the screen cracked.
So my conclusion from having the Kindle about five months, is that it is fairly robust, except for the screen (which I suppose is the case with any e-ink reader). I will buy a new one, as I've been really happy with the whole thing, but this time I'm going to buy that ridiculously priced cover for it.
For more testimonies here, my Kindle has been fairly durable. I haven't been throwing it around or stepping on it, but I have dropped it a few times and the most I have gotten are a few scratches. I have had it since winter last year.
I cracked the screen on my first Kindle DX about a week after I got it. My iPod slipped and landed fully into the screen. Completely screwed it up.
So I'd say do whatever you can to keep that screen away from anything that can fall on it. I was just lucky I was still within the 30-day replacement period. I treat my new one with kid gloves now.
Mine has a few scratches on it from being in my handbag without a cover. I dropped it once too, and the back unclipped. I managed to put it back together. However, sometimes i'll be reading, ill put it down for a minute then come back and its a completely different book. It gets very confusing!
Edit: Mine starting freezing, and restarting. I rang the helpline and they tired to talk me through some fixes but nothing worked. Two days later I had my replacement in hand. I think maybe I had too many books on there. I know it advertises that it has so much space. but I don't think it can actually cope with a lot of books.