Earlier quoted context omitted.
Force touching on the keyboard gives your finger control over the cursor more like a touch pad on a computer. It works really well on the iPhone, not sure if it's available on iPad. But yet again, one of those feature you just have to know about to use.
It was never available on iPad, and is no longer on newer iPhones. It's replaced by a long touch, but this cursor control function has disappeared.
The tradeoff was a 4-hour longer battery so there was probably more gained than lost there but the usable area to move the cursor shrunk considerably (to a long touch on the spacebar only) and makes it harder to use.