Pros: protection and convenience
Cons: weight and price
I love the light weight of the kindle itself, my hand doesn't get tired holding it for hours. But this cover nearly doubles the weight of the Paperwhite, and that's cumbersome. It also does add some bulk. I'm not sure it could be made any lighter and still do what it needs to do, but it is something I notice.
All in all, the weight sacrifice is worth it. I love the convenience of snapping it shut and throwing it in my bag, no worries about the screen getting scratched, and no fussy clasps or elastics to muck around with. The cover allows you to charge with it on, which wasn't so with the ultra lightweight sleeve I made myself from awesome neon chartreuse spandex :)
I also love the way the cover wakes the Kindle when I open it. Not like the button is so hard to push, but that extra little feature just makes it so much easier. I often used to put my previous Kindles down without sleeping them, since they would go into it on their own eventually and it used no power to sit on the page. But now with the backlight, there is some power drain when I'm not looking at it, so being able to really easily close it and turn off that light for a couple minutes is nice.
I got the purple and it's a lovely colour. I previously had a black cover purchased in-store, but I decided to liven it up a bit with the purple. The black was nice because you couldn't see any border around the Kindle. The purple is dark enough that the slight border difference isn't distracting. Once you get into a good book, you don't notice things like that at all.
My only other complaint is the cost. At $40, it's over 30% the cost of the device itself. Because of that, I've never bothered with cases for my previous Kindles, but with the Paperwhite I think they finally got it just right and I'm not intending to replace it any time soon, so I bit the bullet and bought a decent case this time.