Since this book has already been reviewed multiple times on this site, I originally had wanted to attempt to respond to some of the criticisms the book has received. Well it's Dec 31st and I have yet to do so. Perhaps next year.
For the time being, suffice it to say that I believe that most of the critcism comes from one of two reasons: they don't like what Platt has to say and try to cover up their conviction with complex theological goobly-gook... or have read it and are knee-jerk reacting not to what Platt actually says but to what they think he says. Much of the criticism of Radical makes it sound as if Platt is promoting some kind of social gospel or salvation by good works. Perhaps an undiscerning (and/or intoxicated) reader could come away with this conclusion, but what Platt actually says is the exact opposite. Radical calls Christians back to the Biblical truth that God not only saves us from the wages of our sin but saves us for God, glorifying good works (Matt 5:16;Eph 2:10;...etc).
My own criticism is brief: I hate the title. I think the word Radical gets people thinking that this a Shane Claiborne type book from the get go and out come the jerking knees. But the real reason I don't like the title is because what David Platt writes about here is not radical Christianity - its' normative, Biblical Christianity. True, when compared to normative American christianity it will look radical but I think that just shows that what passes for christianity in much of the US (and any nominal christian subculture) is in fact not Christianity at all.
This is a must read if you can read, have $20 and love Jesus.