
I was hoping Apple would realize how unfit and *gasp* ugly the FaceTime icon is. Alas, the app is out of beta and that just didn't happen. The Cupertino company that we all love is giving us one more reason to worry about the recent directions of its UI design.
The icon is horribly lacking the polish Apple got us used to.
First of, the main part of the icon is coming straight from iOS and is by no mean suitable for a desktop application.

While perspectives and materials have their own sub-section in Apple's OSX Human Interface Guidelines, none of them seems to apply to this icon. To quote Apple:
Generally, Mac OS X user application icons are designed to appear as if they’re sitting on a desk in front of you.

Second, the shape to the right looks awful and the lousy highlights / shadows won't make it look any less alien.

However, the real issue with this icon goes beyond the HIG and pure aesthetics.
It is visual dissonance.
The container speaks minimalism and symbolism, while the content speaks realism and high fidelity. Those are two antipodal visual languages, and the way our brains interpret them is significantly different.

Symbols represent a whole; a generic, rough representation of things. We interpret them by adding in necessary details as the image forms inside our brains. Meanwhile, high fidelity representations, especially when they are of a single part from a whole, get interpreted through extrapolation: the brain brings in the other missing parts to form the big picture, the whole.
Back to the FaceTime icon, our brains have to process both languages simultaneously, and that's exactly why it may look 'weird' to you at first glance. Also, to make matters worse, the two elements depict exactly the same thing: a camcorder / webcam.
Trying to be too many things at the same time is probably a bad idea. Keep it classy, Apple.