Despite all the doom and gloom over the prospect of installing iOS 8 on an iPhone 4S, the installation was painless and successful. Started at 12pm pdt, the initial OTA download of iOS 8 took about 90 minutes and the actual verification and installation about 40 minutes on a 32gb iPhone 4s with 6gb of free space. While animations are not as smooth as with iOS 7.1.2, they aren’t chunky enough to be a major distractions and load times are only slightly degraded. If past history is any indication, Apple will tweak the performance of the OS in future updates.
As to whether the update is “worth it” is personal preference. Battery life will be a huge determinant as to the foture of iOS 8 on the 4s.