I actually did upgrade, and had a chance to try the S0 SS and S2 SS (both 42mm) side by side. My view is that if you have the S0 SS, don't need the GPS and don't swim with it, then there's no compelling reason to upgrade if you mainly use the built-in apps. The S2 is faster, but it is often barely perceptible; it's sometimes more noticeable, such as when a map is being rendered. The S2 did seem noticeably faster with third-party apps. I do like the stronger haptic feedback, and the brighter screen outdoors is definitely noticeable and useful. I'll also wear my watch more now that it is more water resistant. Thickness definitely going in the wrong direction. For S0 SS owners, the upgrade is definitely more a luxury than a necessity. I was able to justify it by not getting the Hermes model; the price difference can now go towards the S3...