I've seen considerable deterioration over the last few months. I have had every series watch (including the original), and I think this particular S4 has the worst battery life. But it wasn't always that way.
Some basic facts:
- I have a 44mm cellular
- My typical usage includes a 40-ish minute run with no phone, listening to streaming podcasts via Overcast. The podcasts are resident on the watch (e.g., not streamed over LTE)
- It is unlikely that I would take any calls on my watch via cellular, or that the rest of the day my watch will be out of contact with my phone for anything longer than a few minutes here or there
- As such, it will rarely be independent from the phone's connectivity (but for the run)
- It goes on a charger every night, so starts off at 100% every day
This has been typical usage since the time Overcast hacked together audio uploads, and from the time I got my S4. In the beginning, I never had any battery warnings over the course of a day. Then I downloaded an alternate running app I used, which seemed to trigger the reduced battery life, such that I would receive warnings by the evening. But maybe that's an illusory trigger, and this was happening already...
After going back and forth with the developer, I decided to restore the watch. That made no difference. So I would force kill the app after it uploaded data to my phone. That made no difference too. I ultimately abandoned the app to go back to Apple's stock activity app. No difference still.
So now, on days I do a modest run, it is very unusual for me NOT to get a warning -- e.g., I get call it 16-18 hours life. I have gone to the Apple store, but their diagnostics show the battery is in spec. On days I do a longer run (e.g., 2 hours or so), the watch may die on the run, which sucks (happened this weekend).
For real-time data, I woke up a bit before 6am today, put my watch on, went for a 40min run, otherwise have been in transit or at my desk. At about 1:30 PM, when the watchOS update was released, my watch was exactly at 50%. That seems way too aggressive.
Again, I do not remember such "range anxiety" with prior series (including S3 with cellular). And I never had to fiddle with battery-saving toggles, since I charge every day. Very frustrating...