Just bought it on ebay from a chinese seller with high rating. The item description said it was GENIUNE. But I'm still skeptical. Even thought It works well on my pc the box looks suspicious on the backside. What should I look for to verify the authenticity of this controller?
Please take a look at these photos, and use them as an example if possible.
After some research turns out the controller is actually fake, I ended up buying a legit controller and was able to see the differences, as Jeffrey explained in his answer. The hologram is fake, the Microsoft typography is wrong, the cable doesn't have an inline release, and the worst part is that the thumb-stick behaves like a d-pad, it doesn't have the same level of precision as the legit gamepad. So If you bought this on Ebay like me try to get a refund as soon as possible.