Nothing in that video looks difficult to do at all. I'm not the kind of person that makes combo videos for any game, but I see nothing in that game that looks like it'd be a huge challenge. The animations take so long to complete that you can easily prepare your next move, and your weapons all have such a long reach that I think I'd be able to easily replicate whats happening here.
Now, this
bayonetta video, on the other hand, I would need long, LOOONG hours of practice to get that kind of move to move precision. Just saying in the air like that would is a decent challenge, let alone everything else.
Regardless of what your thoughts on GoW's depth are, a combo video of it just doesn't come off as very impressive or difficult to do. I should mention that combo videos don't necessarily show off depth unless the game was specifically designed for it. I never thought NG combo videos were that impressive either, because NG's skill comes from avoiding enemy attacks and countering than it does from chaining attacks, especially when they are only fighting against one enemy.