I've been using a Gen 3 SPOT for 4+ years and purchased it to let the lady track me when I was off in the middle of nowhere for days on end, and if I needed a helicopter ride.
The Bad:
I find their pricing, website and features archaic and frustrating. Prices keep going up every year, they don't make it easy to pay for a month and then cancel. You have to call in to the CSR to cancel, where they try and convince you not to.
The Okay:
I've not had any reliability issues when it comes to sending non-sos messages or general tracking. I've spent a bunch of time in the middle of nowhere US of A and it's been fine. Also used it on a 4x4 trip earlier this year, hanging from my rearview, out in the Eastern Sierras/Death Valley, again, no issues.
The Good:
Simple device, no screen to break. It's orange.
If I were buying today, Garmin InReach, and don't tell anyone I know it has 2 way text capability.