I just did a trip to the Bahamas and borrowed a friend's Spot Connect.
On the website, you set up the email addresses and/or cell phone number for those you want to get updates. Then you pair your smartphone via Bluetooth and open the Spot App. You can type out the email and will (slowly) send it via satellite. It's only one way; you can't receive anything through it.
The email gets to your pre-programmed list of people, and even includes a Google Map link to where you are. My family (the ones that didn't get to go with us!) thought it was great.
I considered it more just "interesting" than a safety feature; I still had 406/GPS PLB, two VHF radios, two chartplotters, ditch bag (including a third VHF), etc.
