I have a widget - Chuck Norris DB - which basically shows a Chuck Norris joke when selected. The thing is that you might want to scroll up and down in the joke, but as a widget that is not possible and the keys (and the corresponding gestures for Vivoactive) are filtered out by the base platform to select the previous or next page in the widget carousel. (You can get around this by pushing an extra view on top of the widget view, but that is not playing nice with the platform :p - and can confuse the poor users)
The primary advances of widgets over watch apps, is that they are more accessible on the watch. Just a few up or down arrows and it is activated, whereas you have to start a special Connect IQ activity to get to the watch apps. It might not be terrible
many more key presses, but mentally there are a big difference...
The question then is whether you would have
- Used an App, so you can get the up/down arrow behaviour
- Used a Widget, to get in the carousel.