Will bloggers be able to keep the feet of politicians to the fire like newspapers think they do? From a short time reading blogs, I'd say yes.
The criticism is bloggers write from a point of view, likely conservative or liberal. The newspaper people are supposedly neutral, and thus a better fit to play the role of watchdog.
But when there's lots of bloggers, several will usually focus on the same issue. With their different viewpoints, an incorrect or biased view will almost immediately be smacked down. It won't last long enough to become conventional wisdom.
As a Republican watching the pro-Moran and pro-McAuliffe sides go at it, there's nothing that will surprise the well-informed reader. Besides giving Bob McDonnell's team plenty of opposition research, these bloggers are combing over past records and future promises. The debates between sides are much more vigorous than a few political reporters at a few big papers looking at the same information.
With these bloggers, the reader knows where the bias comes from. And there's always someone looking to make a name for themselves, who will work harder and dig deeper if there's something there.