I've had one since Bivy's original Kickstarter, long before they were acquired by ACR. It replaced an older SPOT unit. Its primary utility is for sending an "I'm OK" message to
family members when you are out of mobile coverage. I've only ever used it in wilderness areas around and on the
Great Lakes. For that, it's been quite reliable.
A pro of this generation/style of communicators is the two-way functionality that the previous ones lacked. You can swap text messages and get confirmations, urgent messages, etc.
Cons are the reliance on a
phone tablet for the interface (IMO), and a quirk that happens when you do not maintain a constant subscription: One of the benefits they tout is being able to subscribe for only the months you need it, which is great for seasonal users, but each time you deactivate/reactivate you get a new phone number for texting. This can be confusing/inconvenient for the people you want to communicate with.
I would never rely on one of these for emergencies on the
water, although I considered it good enough for that purpose when hiking/backpacking.