Pros: On paper, assuming you thwart 3 times for max value, you're looking at 6 threat removal and 3 damage (split into single damage hits for easy "tough" removal!) for 4 cost. That is pretty insane.
Cons: A little slow, and in a heroic difficulty game, 4 cost is too high for some heroes to get onto the table.
I think, overall, Daredevil is really strong and is a must include in most Justice decks, barring only decks that need to keep a low cost curve.