My main reason why I don’t use my watch anymore is that it needs to be charged all the time.
Is this an issue with WatchOS, the chipset being used, or the size of battery they have chosen? I know a lot of people out there who do not consider an AW or any other smartwatch because they don't want to have yet another device to charge daily. There are other companies that have achieved very good battery life (Amazfit, Garmin, Pebble), so it is clearly possible to have weeks-long battery life with a feature set that is more than enough for people like me.
I feel like I'll never have an AW until they decide to make an AWU-sized device, but with more battery and fewer hardcore workout sensors. I don't need to dive with my watch, or have it utilize multiple satellites for GPS. What I do need for a watch is to have it last for more than a day or two, so I don't have to bring a charger whenever I go on a trip.
It is the screen (and cell radio, as I’ll note below). Note that when Garmin started putting OLED screens in their watches, the battery life dropped dramatically compared to a watch with similar innards, but a MIP display.
However, Garmin will still beat an Apple Watch for battery life even with an OLED display, because as you point out, the AW is doing a lot more in the background. And firing up that cellular radio is not cheap on battery, either. I’ve got a Garmin 945LTE with an LTE radio, and let me tell you that when that thing can’t find a cell tower, it’ll crank that radio up and burn through a battery in no time. Not so much that I’ve run out, but enough that I definitely noticed a large difference. It makes me wonder if that isn’t the reason the 945 LTE has been neglected and no other adult watches have been made with cell radios.
But, yes, make a “not so much stuff in the background” mode. If I’m in the middle of a 50 mile race, I don’t need email. I don’t need a lot of background refreshing. The AW does have a mode like that, but without going into a long spiel, I think Apple could do better.
For Apple-blessed stuff only. They tightened third-party widget update budget so badly third-party widgets that should provide up-to-date information are essentially unusable. E.g. large Weathergraph widget still works because it shows a day-long forecast, so being an hour old is rarely noticeable, but Fantastical (can keep showing outdated event for a while and miss the actual schedule) or Battery Grapher (can be up to 30 percent points off from the actual battery status) are absolutely unusable.
- no background updates (for non-Apple apps, of course) once the low power mode is enabled
- a buch of long unfixed bugs, like this one https://openradar.appspot.com/radar?id=5568946145067008 - a WidgetKit cache of rendered widgets gets randomly corrupted (race issue when rendering maybe? seems to happen more often with a complex widgets), and once it happens, the specific widget stops updating until device restart (and app has no way of finding out that this happens)