It sometimes happens that a priest is criticized for blogging, considering his many other duties. Such criticisms usually come from someone the priest has upset because what he has written on his blog - generally in cases of the truth - cuts to someone's heart. And rather than going to confession such a person lashes out instead at the priest.
I am happy to say that this has not yet happened to me through my blog, though similar things have happened in "real life."
Over at The New Theological Movement, Father Erlenbush takes a look at the question of clerical bloggers and answers very well. Whether or not he was personally criticized is uncertain and really doesn't matter.