Photostream seems to have updated onto my iPhoto ok, but on this new install on my iPhone 5 the photostream does not seem to be updating all the photos I have turned photostream on and off and no luck
From my understanding, when you activate Photostream on a new device, it will only sync photos from that moment forward on THAT device. So if you have another iOS device with older photos that the device you just activated, they will not sync. However, all photos that you take on either device from that point forward will sync to both devices. I hope that makes sense.
I noticed this when I bought my iPhone 5. I have an iPad with a couple hundred photos in Photo Stream and they wouldn't sync over to my new iPhone. But any new photos I took on either device were syncing to Photostream on both devices. Then I read that this was by design since Photostream is not a backup.