Performance of a new iPhone 4?

Hey guys, my girlfriend is looking for a new phone and I want to recommend the iPhone 4, as it's currently free on Verizon. I know all about how iPhones typically perform, but I'm wondering if the iPhone 4 shows any performance issues running on iOS 6. Can anybody attest to the performance of an iPhone 4 purchased somewhat recently and running iOS 6?

Thanks a lot!