I've been following his blog, it's an interesting read.
He seems to know what he's talking about, as Chuck pointed out he won the Nobel prize in Economics and is a economics professor at Princeton.
And his record isn't too bad. around 06, 07, he was one of the few economists who said there was a housing bubble which meant the economy was headed for tough times. Contrast this with what most economists were predicting - good times to go on forever.