Still not working - i'm another person who bought it without reading the reviews and i'm stuck with a PS3 version that I cant upgrade.
I contacted Sony who told me that I need to speak to Amazon , and I've contacted Amazon who said they are aware of the issue and working on it - but for now *dont* buy this to upgrade (AC4 and BF4 both upgrade fine)
If this is correct I think Amazon need to change the wording / warnings on the page as I'm sure there will be other people who buy it and will not realise it cannot be upgraded - or there will be people who are buying it now with the plan to upgrade later (as the offer should be on until the spring) and will then hit a problem later.
FYI - I just bought the Call of Duty Ghosts - PS3 [Digital Code] for $34.99 and redeemed the code on the http://store.sonyentertainmentnetwork.com/ (on PC). After redeeming the code I also bought the COD $9.99 upgrade from the http://store.sonyentertainmentnetwork.com/ PC store as well with no issues. Downloading now on my PS4!! Paid $44.98, cheaper than paying the $49.96 for the PS4 download so saved some money there..