Software update problem on iPhone 5?

I've downloaded the actual data for the current update (6.1.2), which took about two hours. No problem. But now the actual updating on the phone seems to have stalled. It's been over an hour, and there's been literally no progress at all. Any advice, or perhaps a reason as to why it's taking so long? My previous phone never had any trouble updating, so I'm a little concerned as to why this one is.