After poking around and determining that (a) I'm not alone and (b) Apple is NOT taking this seriously yet, because they think we aren't Doing It Right, I have decided to start actively ignoring the fitness tracker components of the watch other than the step counter and the Stand reminder (and I reserve the option of deciding to ignore the Stand reminder because other people are having trouble with it, too). I took it out of Glances. I turned off all the Notifications and Awards and Summaries. As far as I'm concerned, this thing really is just a snazzier replacement for the Fitbit Flex, the Baby G with the added feature of an outdoor temp and next item on the calendar on the face, which help to make up for the fact that this thing isn't water proof, like the Flex and the Casio. That's basically what I bought it for (that and Apple Pay, which I really should try out some day), and that'll have to be Good Enough.
If you are thinking of buying a Watch as a fitness tracker, you'd better really hate your Garmin or whatever, or you're gonna be disappointed. Maybe they will fix it in a software update.
Oh, and if you reboot your Watch, there's a good chance your Exercise minutes for the day will be erased. Not steps or calories or Stands or whatever -- just the Exercise minutes.