Sometimes there's white flashes on the screen. And I can be sure those aren't intentional, because they're never on the same place or happening other times.

Windows 8.1 Pro x64
MSI GTX 980 Ti
16 GiB DDR3
i5 4690K 3.50 GHz

Everything up to date.

I see also glitches at the beginning. There is a loading screen where the hero falls down.

I don't believe those are graphical glitches. I believe the look they're going for is a "I'm pixelating,twisting, and warping as I'm crossing over into the game world" sorta thing.

I agree it looks buggy, but I don't think it actually is.

As for the white flashes on the screen in the OP, I think this is an intentional occasional lens flare effect that occurs with high graphic detail.