Your users are able to submit feedback on your announcements as long as you have feedback enabled.
From the announcement, your users have the option to submit a summary of their feedback, as well as their general sentiment.
Reviewing feedback
If you have the Slack Announce integration installed, you have the option to be notified when feedback is submitted. You can also receive email notifications when feedback is submitted.
Feedback is stored in the feedback inbox where you can organize it. Reference An introduction to feedback to learn more about feedback.