If I $watch a promise it will treat what the promise is resolved with as the value to watch, which is good. If, however, I $watch a function returns that same promise, $digest handles the promise like a plain object which causes the watch not to trigger on resolve, and anything relying on the watch for the output value (e.g. ng-bind) will receive the promise object instead of the value it was resolved with.

Fiddle (outputs to console)

The check for deferred/promise is in getterFn and that's never used for function calls, should there be a check to see if the value of the expression is a deferred/promise in $digest?