My S0 is starting to become an issue. Battery life has diminished and I often hit low power mode around 6p. It's slow. My aging eyes would appreciate a larger and brighter screen. Very tempted to go for a S4 but would hate to do that and then four months later regret not waiting for S5. However, S5 will likely be an incremental upgrade only and rumors here and elsewhere aren't making it sound like much of an upgrade. Ceramic doesn't interest me that much. Sleep monitor and MicroLED would both be welcomed but it sounds like those are down the road after S5. More accurate heart rate and activity monitoring would be very welcomed. My wife's primary concern with her S4 is that it can't recognize casual workouts like riding her bicycle to the store and it doesn't provide accurate data for bicycle rides. I would love to have accurate power info (e.g., in place of powertap, pedals, etc.) but I'm not sure if that's really possible to calculate. Any insights or thoughts welcomed.