Students' feedback should be, in my opinion, more helpful, provided that the students are some what mature in nature and understand the significance of their feedback.
This is because of the fact that the feedback from students, is based on their direct experience with the teachers.
Students evaluations is primarily focused on instructor’s teaching performance and is influenced by how easy and popular the instructor is. Peer evaluation can provide a broader view of teaching effectiveness and a more objective assessment of teaching than students evaluations.
All the three - Students, Colleagues and Employers are crucial for a teacher, however, students feedback as the bottom-up appraisal is very important because they are the real judge to measure efficiency of a teacher.
As a student, I can easily say that my feedback on an instructor would be categorized under 3 partitions .
1- Performance
2- Proficiency
3- Experience
To give a clear judgement on the instructor performance i will have to reflect on my own performance and my fellow students on the assessments provided by the instructor , such as quizzes , exams and assignments. This is a directly proportional judgment as our performance as students will reflect as a key performance indicator for the instructor .
Regarding the 2nd criteria , the proficiency factor is a little tricky as sometimes an instructor may be conducting a course that he of course studied and acquires a significant level of knowledge in it but on the other hand is not interested in as it is not his area of masters . This factor is easily determined from the amount of enthusiasm / interest placed in the course , which is something in my opinion can be only determined via students feedback .
Last but not least, the experience factor can be determined by a student feedback if the student for example asked a question to the instructor and the instructor failed to provide a satisfying answer for the student . Sometimes an instructor might have a great deal of experience in a subject but his delivery is weak and he is unable to convey the message clearly to his students , this in my opinion is a vital key in the pedagogical process , and it is not up to the students neither the colleagues to determine but it is up to the educational board who hired the instructor to see if his delivery is adequate enough or not .