Amazon, Best Buy, and GameStop are all trying extra hard to sell you a copy of Final Fantasy XIII-2. Each of the retailers is offering an exclusive extra to pre-order customers in North America.
GameStop will offer you an alternate costume for Serah. Serah, the younger sister of Lightning, is the main character of FFXIII-2. The bonus costume will be usable for the whole game. GameStop hasn't provided a picture of the costume on their FFXIII-2 product page, though, so it's tough to tell what you're getting.
Best Buy's pre-order customers will receive Final Fantasy XIII –Episode i. This is a hardbound novella that focuses on the time period between FFXIII and FFXIII-2. Seems like a solid pick-up for "lore nerds," or anyone who finds the FF games a bit tough to follow.
Arguably the best incentive comes from Amazon, though. Pre-order with them and you'll get an exclusive coliseum boss battle against Omega. Based on Omega's from previous FF games, this is going to be a pretty tough fight. The kicker, though, is that he'll join your party after you defeat him. Solid.
FFXIII-2 takes place three years after FFXIII. Lightning has gone missing and many believe she's dead. Serah, however, is convinced she's still alive and embarks on a quest to find her.
The game makes its debut in Japan on December 15th, so expect to see reviews start popping up around then. North America will receive the game on January 31st. The PAL territories are bringing up the rear with a February 3rd launch.