No, you cannot roll back to 6.0.2.
Have you tried restarting or resetting your iPhone?
Restart: Press On/Off button until the Slide to Power Off slider appears, select Slide to Power Off and, after the iPhone shuts down, then press the On/Off button until the Apple logo appears.
Reset: Press the Home and On/Off buttons at the same time and hold them until the Apple logo appears (about 10 seconds). Ignore the "Slide to power off"
I posted the below fix on another related thread.. but this is what I found:
After an OTA over WIFI upgrade to 6.1, Bluetooth stopped pairing with any device, and lost its existing paired settings. Furthermore, I had the following issues:
1. Could no longer join a secured WIFI network (it threw an invalid password error)
2. BIG ISSUE! Could no longer back up in ITunes ("Could not back up because an error occured")
Luckily I had a iCloud backup from 4 days previous to the upgrade. The only way to resolve this was to do a complete RESTORE of the phone (in iTunes), at which point it puts a clean and full install of iOS 6.1 (instead of a broken upgrade). After restore I recovered the iCloud back up.
My advice if you are having this same issue is do a full restore as soon as you can especially if you are unable to do a backup. Otherwise the longer you wait the more data you will lose.
The problem is not iOS 6.1, it is the actual upgrade procedure which screws up the phone.