Microsurveys should be able to support general sentiment questions that go beyond the traditional Net Promoter Score's question of "How likely are you to recommend?", usually on a scale of 1 to 10.
I'd like to see support for two kinds of sentiment survey. One is a simple happy–sad spectrum, which might use emojis such as these:
The other one would represent most/all of the six basic emotions: sad, mad, glad, afraid, surprised, disgusted. The corresponding emojis might be these:
This second set is less about how strongly you feel and more about the variety of emotions that people feel. A person who is a little annoyed and a person who is extremely angry would give the same answer, but a person who was anxious would give a different answer than a person who was sad. (It would be simplest to pick only one answer.)