I'm disappointed with the lack of notification granularity, at least as it pertains to my iPhone / non-Apple Watch setup (Garmin).
On my watch I'd only like notifications about meeting reminders, scheduled reminders, and possibly google maps notifications (directions) while biking. I don't want my watch to buzz when I get a message. I do want to see a badge / bubble on my phone though. With iPhone / Garmin, it's all or nothing.