It's an interesting concept but not yet a replacement for the Garmin inReach. In addition to concerns about replacing a rugged piece of gear desgined for outdoor and emergency use with a relatively fragile iPhone there are technical limitations.
From Apple Support https://support.apple.com/en-us/HT213426
Emergency SOS via satellite availability
To use Emergency SOS via satellite, you need an iPhone 14 model.*It will also require an iOS 16 software update coming in November 2022.
You also need to be in a place with no cellular and Wi-Fi coverage.
Emergency SOS via satellite is available only in the U.S. (including Puerto Rico and the U.S. Virgin Islands) and Canada.
International travelers who visit the U.S. and Canada can use Emergency SOS via satellite, except if they bought their phone in China mainland, Hong Kong, or Macao. Emergency SOS via satellite isn't offered on iPhone models purchased in China mainland, Hong Kong, or Macao.
Emergency SOS via satellite isn't available in Guam or American Samoa.
Emergency SOS via satellite might not work in places above 62į latitude, such as northern parts of Canada and Alaska.
This article goes into more detail https://www.digitaltrends.com/mobile...-availability/
The Apple SOS feature seems to be less reliable and requires more from the user to work properly than the inReach. Tracking the satellite, keeping alignment and more interaction required by the user.
Also the iPhone's satellite communicaiton is emergency only, no general text or tracking that the inReach offers. I have used both in urgent situations that had the potential to become emergency situations. Without going off topic I once had the USCG Morrow Bay standing by in case the urgent developed into emergency.
Apple uses the same term as Garmin for their emergency communications. SOS. However I wonder if Apple's response system is a robust as Garmin's? Garmin's IERCC has a proven track record of success.
Additionally Garmin offers search and rescue insurance that will help with the costs of a rescue if needed.
So, at this time, for anyone who cruises remote areas or outside of the US and Canada the iPhone is not a replacement for the inReach. Apple will likely improve that in future, who knows when.
For me a cell phone will never replace a dedicated well designed piece of emergency gear. The cell my be the first thing I reach for because it's easy and I'm familiar with it. But it won't replace the EPIRB and inReach which are what I carry aboard.