I went from S6 to S9 when the battery life was no longer getting me through the day, and then to S10. Other than battery life (which really is a very good improvement) I find nothing different in terms of how I use it - indeed, the loss of the blood O2 sensor means the S10 is less functional for me than was the S6. The thinner form factor feels like a minor upgrade, but otherwise most of the new features (apnea stuff, swimming stuff) are not things I make use of. I don't regret the upgrades - thanks to lucky open-box / trade-in deals the S6>S9 upgrade cost about the same as a battery replacement and then the net cost for the S10 upgrade from S9 was about $30 for me. So, I'm still happy with it, but I can see why people would not feel compelled to upgrade except for battery life.