I just finished reading it a few days ago. It's definitely worth reading, but not as funny as his Rush Limbaugh book. The first half of the book is a bit to serious for me, it only has a few chuckles in it. Things pick up in the second half, though, with some real laugh-out-loud moments.
I bought Lies the day it came out in Omaha. I devoured it that same afternoon/evening. It is hilarious, insightful and made me sad over the state of the U.S.'s "media." In my view, the First Amendment's guarantee of freedom of the press is the most powerful check on government abuse of power. Even more than America's recent sad chapters in Iraq; the budget; etc., I truly believe that the history of our era will revolve around the media's abdication of its power in exchange for bucks.