I've heard that it's dusty and can mould quickly, but my dad makes hay and he's happy to let me take the loose stuff, so...Well, I'm not passing up free bedding.
In my opinion, if you're letting it get mouldy, you're not cleaning out your chicks often enough. I change it at least once a week, every four days as they pass two weeks, and I keep my waterer on a piece of wood so that the bedding's not getting wet. The chicks like to peck at the occasional seed head that they kick up. Thus far, I've not had any problems.