I was also offered iriver Story and didn't know it had higher resolution on the screen and I didn't do any research at all and chosed the Pocketbook 622, mostly based on that I didn't like the keyboard on the iriver.
The iriver is much better supported in Sweden, you can buy cases and there are a several retailers selling them. With Pocketbook there is almost none, so I hade to buy a case from Hong Kong on Ebay.
But I think that higher screen resolution 1024x768 makes a better improvment when it comes to reading. But I like my Pocketbook 622. People are watching me when I use it in public and asks me what it is. Sometimes I tell them that it is a new prototype of the ipad 5 and Apple is now giving up color in advantage for longer batterylife… You should se their looks on their faces. Sometimes they think it is an old handheld computer from the beginning of the 90's.