5 games million sellers is not by itself impressive.
What is impressive is the gap between 5 for PS4 and just 1 for X1 (COD of course). Thinking people made threads complaining people with PS4 weren't buying enough games.
And more than twice more AC4 sold on PS4 than X1. Wow. Apparently the 1080p patch has been well advertised by those videogame websites everywhere!! Thank you Microsoft for your first day resolution parity forcing developers to release patches freely broadcasted by every videogames enthusiasts, now everyone knows AC4 (and COD) on PS4 are in higher resolution than on X1 and it cost Sony nothing.
Sony is back with a vengeance and will use every mistakes done by Microsoft. No prisoners.