This is only a "radical" concept if you haven't been practicing it your whole life. ;]
I do like the article, though. I think it makes two important points about radical honesty: A) it's difficult to do, you really have to force yourself do it; white lies and "politeness" are far easier. And B) everyone will call you an asshole whether you mean to be one or not. Radical honesty certainly isn't for the weak of will, or socially frightened.
Personally, I think the rewards are well worth it. There's way too much bullshit in the world. Anything we can do to kill some is tremendously liberating.