I feel like your comment is from 3 or 4 years ago. It's been at least a few versions of iOS since you can respond directly to notifications, replace the keyboar

I feel like your comment is from 3 or 4 years ago. It's been at least a few versions of iOS since you can respond directly to notifications, replace the keyboard, add widgets to the 'today' screen. Background processing works fine, and was implemented in a way that doesn't completely drain the battery. The hotspot is designed to turn off if the clients have not been transmitting or receiving data for a period of time as a battery saving measure. It doesn't do this if you tether over USB though.