I heard it said by potential iPhone customers that 64GB isn't enough storage.
I have always said, well that's what iCloud is for. Additional storage in the cloud and off your device. Of course the beauty of cloud storage when implemented well is its almost seamless and indistinguishable from items stored on your device.
In addition it's brilliant for backing up and sharing stuff across many devices, keeping them up to date.
If iPod is anything to go by, the classic at 160GB has enough storage for nearly all your entertainment needs. What if the hard drive in an iPod classic could be shrunk further to find in the confines or an slimmer, lighter iPhone. What If that shrunk hard drive was able to take advantage of Apples fusion drive, first introduced on the mac lines. Frequently used items are kept at the ready on speedy flash storage, while infrequently accessed items go to the hard drive. The best of all worlds?
Faster, and therefor a smoother proposition.