I got a fitbit charge 2 about 9 months ago when I was experiencing some health issues. I bought it because they advertised you could download your data and do statistics. I found that was a lie, you could not download raw data, only the useless canned reports on your data that they are willing to provide. There was a third part app that allowed you access your raw data, but fitbit had it shut down. On top of that, I found the heart rate data readings, the only thing I actually cared about, to be incredibly buggy. I can take it off and watch it calculate various heart rates from 50 bpm to 180 bpm with no pulse to base those on. As a result I have an unworn fitbit sitting in my drawer. Will not purchase again.

As a footnote, I did find the sleep statistics they provide a little bit interesting, but again they're not accurate enough to base any judgements on. But still interesting.