http://arxiv.org/abs/1401.5761
¹ You should question to what extent they're journalists, when their employer is a for-profit entity existentially threatened by the subject they're reporting on.
I really don't think that this is true. The useful bit of peer review is changes made to the original paper as part of the peer review process (both for accuracy and clarity of exposition). No feedback from arXiv readers has yet been incorporated into this paper; perhaps in a few months there will be an updated version that includes such feedback. Until then, people will have to search the net to get a feeling for how the wider field views his ideas.
In terms of feedback from conferences, plenty of results are presented at conferences prior to publication in Nature and other journals, so I doubt there is any difference in the review level here.
I imagine it has actually been reviewed by some of Hawking's peers before he published to the internet. I know that's not the generally accepted usage of the phrase peer review but I think it is probably becoming more normal practice.