What is the blooming point? Everyone who has a PS3 has a PS3 controller! The only reason you would need another is if you wanted to play splitscreen (Which MW3 doesn't have to my knowledge) or if you liked the different shape of the controller.
I'll give credit where credit's due, the controller does seem a lot more natural than the standard PS3 controller, but then there are exactly the same style of controllers being sold on the link given that have all the features, the only difference is literally the colour. There seems to be no word on pricing yet, but anything over $35 (the price of the same controller unbranded) You're just paying for the MW name, which no one will ever see because it's stuck in your bedroom.
PS. Here's the XBOX 360's Modern Warefare 3 controller
http://www.xbox.com/en-US/Xbox360/Accessories/Controllers/Modern-Warfare-3-Wireless-Controller
It's $60 compared to a standard controller being $50, so that's $10 for branding, which isn't as bad as I first thought, but why are the standard Xbox Controllers almost twice the price of a top-of-the-range PS3 controller?