With the latest point release, iOS 8.3, your faithful iDevice (an iPod Touch 5g, in my case) no longer gets the GPS data stream from the SE. Here's a page that reports on that for a couple of other GPS receivers of the same vintage.
I fixed the problem by backing up the 'pod, reinstalling iOS 8.2, then restoring the 'pod. Apple makes the previous point release available for a limited time, but I don't know how long that is. I have a copy of 8.2 for the iPod Touch 5g, which can be made available to others if needed, but if you have another iDevice, you need a version of iOS for your specific model. So hurry! Or don't hurry, if you haven't yet installed 8.3.
Until the glitch with 8.3, my experience with the SE has been trouble free. I use the Safety Plan, and almost all my message traffic is Preset Messages. So far, no additional charges beyond the $12/month. Worth it. I use it a lot, often skiing solo in the wilderness of the southern San Juan mountains in Colorado. Due to thin cover, skiing is nearly over without some big storms.