I will agree that Matt can seem a bit cocky, but what I do like about him is that he experiments with many different extreme diets and then writes about what he experiences. One of the reasons for his "puffyness" is that he was working on a diet that he ate tons of calories (High Everything Diet) to determine if it will make positive changes to metabolism/health, and I think he is on to something as well.
I have shared some emails with him and he has been very nice/helpful each time. I don't plan to go on an all milk diet, nor do I plan to go back and try a vegan diet, but I have moved from about 5 meals a day to 3 larger meals after reading some of his work.
Just like [URL="http://wholisticfitness.com/"]Steve Ilg[/URL], he may seem a bit arogant initially, but I think his heart is in the right place and he does the work that many people won't do so that he can share his experience with them. He is an interesting guy.
I don't really see why there's so much controversy between him and the rest of the paleosphere. He's very much anti-sugar, anti-frankenfat, anti-processing, anti-crap. He's skeptical about the carb hypothesis, but then again, so is Richard Nikoley. To what degree he's pro-carb, he sticks to real food; mostly a lot of potatoes from what I've seen, coated in boatloads of saturated fat.
Even if we're to assume that whole food carb sources are bad, they're still not even in the same realm as processed foods. Just like with the vegans (well, the ones who live on avocados and coconuts, not the ones who live on soysages), I have to conclude that the enemy of my enemy is my friend, as well as a grindstone against which we can sharpen our own understanding.