The biggest change to Apple's smart watch lineup is the addition of LTE connectivity (a $70 option over the non-LTE Series 3). This new Dick Tracy style watch will allow you to make phone calls (with your same number), send and receive messages, use internet connected apps and stream music from Apple Music.
The new OS, which will work on all devices, brings improved exercise and heart tracking, Siri finally can speak back to you.
The heart rate functionality is dramatically improved tracking your heart-rate pre-working (resting), during and post-workout. It will show how your heart health is improving over time ( faster recovery, better resting heart rate, etc.).
They have also created a new standard that will allow your watch to talk to new types of gym equipment. This means your watch will be able to log gym equipment data (speed, incline, etc.).
The Series 3 Apple watch has the same dimensions as the existing Series 2, and they promise similar battery life. You will be able to pre-order the new watch this Friday (September 15).
We'll have to wait and see what carriers charge to add this new device to your smartphone plan. Hopefully, it won't be $10 a month.