I upgraded to 12.1 last night and I own an iPhone XS 64GB and I must say the battery is phenomenal. I took my phone off the charge at 8:30 this morning and it is 7:30 EST and I only went down 20 percent? I've used my phone to send text messages, browse forums, watched a couple of videos and made some calls. This is really good. I don't think my battery was ever this good in 12 hours on a new phone.