You'll need to have a verified account at Mt. Gox to use Dwolla as a withdrawal method (if I remember correctly), but yes -- Dwolla is a fantastic and inexpensive withdrawal method. There is one caveat in that you never know how long the withdrawal will take. It could be hours, or days (and weeks even, when there is an imbalance). Worst case scenario your withdrawal request is queued up, you cancel it and figure out some other method.
Is it safe? I'm verified and just added my Dwolla account and that's verified too. Only 25 cents to withdraw? What's the catch? Bitinstant charges you 9% to withdraw to paypal lol I withdrew $50 as a test... How do I cancel queues?