Writing 'the assessment was unfair' doesn't help us very much, you need to tell us why. For example you might say 'the assessment was unfair because some of the questions that we were set hadn't been covered in classes'. Also tell us why you liked something, however writing 'the module was great' isn't very useful to us. Instead you might write 'The module was great, the lecturer was good at explaining things and always encouraged discussion in the class'.
Telling us 'assessments should be scrapped' isn't realistic, we need a method of assessing what you have learned. Instead tell us why you didn't like the assessment. 'I thought that there were too many small assessments, I'd rather have one or two more detailed ones'.
Focus on the issue not the person
Do not write anything that is offensive or might be considered personally insulting. If we think that your comments are offensive we will exclude your questionnaire from the survey. You might say 'I found that the pace of the lectures was very slow and there were many digressions from the point. We seemed to discuss a lot of things that weren't relevant to the module'.
Tell us how we might improve. For example 'I found the seminars really helpful but we only had one every other week. I think having a seminar every week would really help me to understand the subject'.
Provide relevant feedback
Try to provide feedback that is relevant to the module. Writing that there isn't enough provision in the canteen for vegans isn't relevant to you module. There are other ways to provide feedback on issues that are not related to your module.