The Rock and CM Punk were rehearsing their Royal Rumble match on Sunday afternoon in the hours leading up to the Royal Rumble. The finish was kept top secret from the rest of the WWE locker room - with WWE even hanging a curtain around the ring so nobody else would know what the finish would be.
Some CM Punk fans were upset that Punk was pinned after getting hit by the People's Elbow, opposed to a Rock Bottom, which is a more devastating move. The reasoning behind this is that CM Punk was ranting about how the "people don't matter," so The Rock beat him with the People's Elbow.
The Rock will give the WWE Championship a ton of exposure as he makes the media rounds to promote his upcoming movie releases in the months leading up to WrestleMania 29.
(Source: Wrestling Observer Newsletter)