Another advanced feature on our Professional plan and above is what we call Feedback Topics. These can be switched off/on for each of your survey templates, and allow you to add an extra multiple choice step in for those that rate you a 0-6 (Detractors), 7-8 (Passives), or 9-10 (Promoters).
To turn this feature on just click the cog-wheel, and then select "Settings" from the drop down. The feedback topics are on the left hand menu just under "Survey Email".
Switch this on, and you will see the default tag ideas; you can remove these and add your own custom topics, but you are restricted to 6 in total.
These are wonderful if someone ends up not leaving a comment, this option helps you get a bit more information from them about what you can work on. It asks the question "What is the main reason for your score?", and then gives them a chance to select this from the options.