BE WARY OF REDEEMING YOUR SIGNATURE EDITION CODE BEFORE THE OTHER DLC IS ADDED TO THE PLAYSTATION STORE.
If you got the Signature Edition of this game you get a code to unlock extra content. You use it in the PSN Store like usual. Well I tried that and nothing got downloaded, and now my code doesn't work. So I may be screwed out of the extra content for now.
It may have something to do with the fact that the other AC:R DLC is not in the PSN Store yet. I suggest waiting to use your Signature Edition code until the new DLC is added to the PSN Store.