I think you guys are over-reacting a bit to this review. I just read it and didn't find it negative, at all. They are confirming that McLaren delivered exactly what they said they would. It's just not their cup of tea. They would sacrifice some of the outright performance for more "playfulness on the limit". I wouldn't- but that is fair.
You have to remember, when most of these journalists (at least the ones without real racing experience) refer to oversteer and handling on the limit, etc., they are really talking about very low speed (i.e. second gear) induced power slides. They are intentionally upsetting the balance of the car, usually with a scandinavian flick of the steering wheel, or some other technique, to get the car to drift. In effect, they really are just "playing" with the car; you would never do this while trying to drive quickly.
McLaren's USP is not about playfulness and "fun". Is that a mistake, as far as their marketing strategy? Who knows, at this point, but my instincts tell me that they need to stick to their vision and establish the brand based on unique traits. They are about high performance and, above all, bleeding edge technology. Their Formula One racecars, historically, were always first to introduce new technologies. Even Bruce McLaren, himself, was a pure innovator in motorsports.
The preferences of journalists these days, especially the Brits, have been trending towards the "fun factor". I can't really blame them, as the performance index of most cars, even the SUVs that football/soccer moms drive, has been far beyond usable speeds for many years already. But, will that stop the market from demanding ever-increasing performance, just because the journalists wish it? Again, who knows, but I doubt it. In fact, it seems Auto Express's readers "get" the 12C, even if the journos were hoping for McLaren to build something else:
http://www.autoexpress.co.uk/carreviews/performance_car_of_the_year/274195/the_reader_vote.html