Hi. My iPhone is currently jailbroken on 5.1.1. with absinthe. I am considering upgrading to the latest ios version 6.1.2. using the evasion untethered jailbreak. Firstly is it worth it and secondly what are the stages for me to upgrade. Thanks
If it ain't broke, don't fix it. If there's nothing wrong with your 4S as is, there's no point in updating. TBH, there really isn't a huge boost by upgrading to iOS 6. If you still want to, backup your device using iTunes, then backup your Cydia packages using apps like OpenBackup and such. Restore using DFU mode in iTunes. Once you're on iOS 6.1.2, download the latest version of Evasi0n through the Evasi0n site, and jailbreak your device by following the instructions.
If you need visuals, here's a great sticky for visual instructions.