@ manara - You've probably just been unlucky with the dead/stuck pixels (and very unlucky with the cracked screen), and you could order a Paperwhite to give it a try, but there's no guarantee you won't have similar issues. It is good that you've had no problems with returning your Aura, as concerns about this were one of the reasons I opted for the Paperwhite over it. Incidentally, I ordered two PW's before settling on one I was happy with.
IMHO, the fact that both the Aura and the PW use the same kind of 'advanced' technology (a capacitive touch screen and front-lit), sell them at a very competitive price, and both have had some quality control issues is not a coincidence. Although Amazon have improved it slightly from the original PW1 to the 2013 PW2, it seems combining the capacitive touch screen and front-lit tech and getting a consistent result is a little more difficult that the older infra-red touch screen & front lit.
Personally, after four attempts I'd give up and consider another option. You could order a PW and give it one chance, and if you don't get a good one, return it for a refund. Or maybe even try the slightly older Kobo Glo if you are happy enough with Kobo/WH Smith. Or settle for a Kobo Touch (on offer at £30) without the built-in light and consider it a stop-gap for a newer, improved version of the Aura in another year or so.
Edited to add: forgot to say about the screen damage, all ereader screens are pretty fragile, you might not have dropped it but did you carry it in a bag and perhaps something else in your bag was nudged against the screen? It's sometimes pressure like this that causes the damage, and then the slightest bump (even laying it down on a table) will be enough for the crack to appear.
Last edited by soulfuldog; 01-06-2014 at 04:56 PM.
Reason: Forgot to include comment about screen damage