Using Absinthe is way easier than Redsn0w or any other jailbreaking tools, since you only need to plug the devices and hit the button once (yes, once). It will do it's magic automatically and when it's done, you can safely reboot your devices and got the untethered.
Small warning, taken from FreakGeeks
Important notice for those who are wishing to get the iPhone 4S unlock, don’t update your device to the latest iOS 5.0.1 because the iPhone DevTeam has announced that they got a exploit for the iPhone 4S unlock. So stay on the iOS 5.0 with the very first buggy baseband. The iOS 5.0.1 Absinthe also works on the iOS 5.0, that means you can jailbreak your device while staying at iOS 5.0.