Ask HN: After iOS 11 problems with battery. I am alone?

After updating to iOS 11 on my iPhone 7 ( <7 months old), I had several issues with my battery life.

Initially the phone would act very weird and would turn off whenever below 20%. This was (partially) fixed by updating to 11.1.1 but the phone now would act erratically. The battery would suddenly drop several % points (like from 30% to 21%, in a matter of minutes).

I have interrogated both online Apple support and have also gone through an intensive (1h) session with one of their geniuses. However, apart from having me walk away with all my settings disabled (no background activities, no location updates for any app, no automatic background intensity, ...) they have done nothing else. The battery is still acting erratically, and they claim it is still in their GREEN zone. So not much from them.

I don't think it is normal to pay a phone that much (I got mine for >£650) and then having to disable all its features to still have it not working.

So I am asking, is there someone who shares the pain or am I alone in this? Is there a "bug" in their iOS 11.x.x that I am not aware of (and probably neither they)?