They are as noted prototype devices – with no announced release date – so it's completely in the realm of possibility that the camera simply isn't ready yet. Of course that doesn't excuse the misleading video and pictures Nokia used to advertise it.
Plus, it's compared to a photo they took with "a competitor's phone". Even I can take an amazingly crap photo with my camera-phone, it's not hard.
Not trying to feed the anti-Nokia, I've always been curious of these types of things.