Considering the prevalence of 'shitty' games that he's done over the past few months, probably something along the lines of:
'this is the most I've ever wanted to fuck my computer, but I can't work out where my dick goes'
... or not.
In all seriousness, he'll probably bring up the whole 'do games really need sequels' argument and mention something like 'if you liked Portal 1, then you'll love Portal 2, because it's more of the same' (it essentially is, but with minor gameplay changes and better graphics). But since it is a sequel that follows up such a cult game and stands well by its own strengths, much of the review will be to do with the story, methinks.
