The ECG feature is not new or exclusive to Apple. A few companies announced similar smart watches at CES, earlier this year.

I have a Fitbit HR right now that does heart rate. But Fitbit's app really sucks. And the device really doesn't do the best job at tracking my heart rate or getting my sleep cycles right.
I've been looking at the new ASUS smart watch that will do blood pressure. But I have no idea when it will come to the US.
It's the only thing I use these smart watch like devices for, medical! I have no need for it to do text, email, phone calls, or anything else beyond medical purposes.