At a former employer we all got trained on this and used it for a few weeks before reverting to our old bad habits :)
I generally approach these kinds of methods with some skepticism - it is a bit 7-habits-ish - but one thing I did like about this one was that you could look at it as "design patterns for productive meetings", in that you could ask yourself what the goal of the meeting was and work from there to identify the right way to structure it. However I definitely attended too many meetings where the goal ended up being following the 6TH plan to the death rather than reaching a real goal.
I quite like this system, though not as a "brain" thing as it seems to be presented here, but as a social system for working together better.
Just as "brainstorming" is just a way of saying don't jump down my throat with questions and problems when I'm trying to think, the six hats system lets people say in a meeting "I have a bad feeling about this" and acknowledge their feelings rather than try to shoot it down technically because vague misgivings aren't as valued as they should be.
 Apparently brainstorming doesn't work, though I think the research compared people coming up with ideas alone, whereas brainstorming is supposed to make communal idea generation better. Maybe it still does that, but still can't beat independant idea generation.
Having tried to implement a certain form of this, I can say that forcing yourself into a certain mode of thinking, top down, is EXTREMELY mentally taxing. It's very difficult to keep up the mental focus necessary for an appreciable amount of time, and I would not be surprised if this actually impeded mental performance on an individual level because of the effort involved, though it's possible overall group performance could still increase.
I used to work at a company where we used this method to tackle especially complex or politically sensitive issues. I have to say it was really effective at pull everyone together to have a constructive conversation. I wouldn't recommend it on a day-to-day basis, but for larger issues or for issues with several ideas in strong competition, this is fantastic.
De Bono's Six Thinking Hats is part of the reason I named my security startup "BlueHat Security, LLC" (http://www.bluehatsecurity.com). Unfortunately, now it's on hold. So, maybe I didn't see the big picture after all :-)