Most people don’t want the government to have their refund longer than it has to. We already know that as a result of the October 2013 government shutdown that the start of tax filing season is going to be delayed by a few weeks. That in and off itself will delay early season filers in receiving their refund.
A potentially bigger disruption is the possibility of another January 2104 government shutdown. If that happens refunds could be delayed even more- potentially for several months. My general word of advice for individuals is this is not the year to overpay. You don’t want to incur underpayment penalties but you also don’t want money tied up unnecessarily for an extended period of time. You can avoid substantial overpayment by lowering estimated tax payments or reducing withholdings. Note that if you reduce your withholdings be sure to change them back as you will be given a surprise in 2014. As always, speak with a CPA about the specifics of your situation.