Yeah... definitely not looking forward to seeing people doing the things in the video, considering that people taking pictures with their iPad really looks odd to say the least. For me, seeing people take pictures with the iPhone doesn't bother me that much, since its size is close to point and shoot cameras. The iPad on the other hand, is not really compact, size-wise.
In terms of purpose, photography shouldn't be the primary reason why a person buys either devices. They just come with a camera feature that can be used... Like I mentioned, the iPhone is at least a reasonable size, but the iPad, is one giant touchscreen with one main button on the bottom. If you want to zoom in or out with an iPhone, it feels a lot easier than holding the iPad in one hand and adjusting the settings with the other.
I guess what I'm trying to get at is that the iPad isn't exactly there yet in terms of features for photography. On pretty much all cameras, digital and film, the standard for the shutter release is to be on the right side of the camera. However, the iPad's "shutter release" is smack dab in the bottom center. So unless you have a hand that's big enough to have your thumb reach the middle of the screen while holding the iPad up, it's likely that you'll be balancing the iPad with one hand and hoping that you hit the button when the horizon is actually horizontal.
Although there's a bit of time before Google Glass is released, I hope the features in terms of taking pictures with it are polished, especially since the theme around Google Glass seems to be around connecting and sharing experiences easier, and photography is definitely going to be included in that.