Is the Adwords keywords planner accurate ?

[atakala]

Hey guyz,
As you guyz do, I base  all my seo effort into the keywords' traffic and quality which I can get from Adwords Keywords Planner.
But this post has confused my mind .
It' says the average searches doesn't exactly the average searches.
And everything is okay here now I can say that of course it's not %100 accurate.
But the shocking part is he gives an example of how a big gap there is between real searches number and adwords keywords planner tools give us .

What do you think guyz?
Can it be true ?
(And also last time I asked a question, Randy has replied me, If possible please Randy do it again :D.)
Best wishes.

[Linda-Vassily]

The date on that post is 2010-- a lot has changed about Adwords since then!
Here is a more recent post, hot off the presses: http://www.business2community.com/marketing/google-updates-adwords-keyword-planner-tool-advertisers-need-know-0861602