I have been primal since February 2012. No more "brain fog", stable moods, no hunger, and 60 lbs lighter (after a 4 week plateau at about -40lbs).
It all makes sense, though I do perhaps eat more fruit that the average prescribed - but it works for me.
Ancestral Health Info - My blog about Primal and the general ancestral health movement. Site just remodeled using HTML5/CSS3 instead of Wordpress.