Ease of replacement
I love that I can order the replacement, have it come in, and then mail the old one back out without having a lapse in monitoring. I am leery of sending out my new(er) logger for the replacement, but the above ease makes it more appealing. As for basic training of the logger, there could be improvement on the training guides as they are not as intuitive as they could be. Trying to search a specific need, such as changing a battery and how to relaunch your logger, is hard to find and often confusing to others trying to do this independently.