Students should have the ability to share their experience of various instructors. As long as third party websites like ratemyprofessor exist, the students will always be able to share their experiences with each other. It is also valuable to the institutions to get feedback from the students. If a professor is an expert in their field and brilliant in the lab but just not any good at teaching intro level materials, that information needs to make its way back to the administration.
Yes, students should be allowed to evaluate their teachers and professors by giving honest opinions of their course content, teaching style, amount of homework assigned, and also to submit ideas for making the classes more interesting. This should be two way communication which I think would greatly improve the classroom experience for our kids.
There is no better way for a teacher to know how he or she is doing than to get an unbiased evaluation from their students. Kids will be extremely honest about the teacher or professors performance. It would be based on their own basic understanding of the class material being taught to the students.
I definitely think that students should have the right to evaluate and judge their teachers and professors. It shouldn't dictate whether their teachers and professors have a job though. But I think it's a good way to decipher if there is enough of a case in regards to if a teacher or a professor is doing their jobs well.
I don't think students are the best people to evaluate teachers and professors. Firstly, they have no real experience from a variety of teachers teaching the same subject, with which to compare, and secondly, there would be a danger that any evaluation would simply end up as a popularity contest, with students marking down teachers they don't like.