I've had BF4 for PS3 and when PS4 launched in Europe yesterday, I got myself one and opted to simply upgrade the game to PS4 via PS Store.
After literally hours of downloading and installing, numerous problems have been encountered.
The most annoying one being the loading screen before starting multiplayer just won't move on for more than 10 minutes. Heck, the loadscreen kept looping the soundtrack for 4 times. to put it into perspective.
I thought I have done wrong, so I deleted the application including the update files, and started fresh. Followed the specific instruction by not loading the disc while downloading the update.
But after another 4-hour agonizing episode of waiting for the game to install, no improvement has been indicated.
So yeah. I finally emphatize raging BF4 players who paid good money for a bit of fun.