I think that it is very important for students to be able to evaluate their teachers. No one knows how the teacher performs than the students and its important to take that into account.
When students are in school for around seven hours a day, five days a week, teachers have a large involvement in the students lives. It is important because if students are forced with a unresponsive, unhappy and uninvolved teacher, they face a dull and regretful year of learning. Its only fair to give students responsive and interactive teachers to maximize our learning experience.
Teacher evaluation is important because it allows for teacher to be more accountable, and these evaluations should be taken into account of placement and management of teachers. If teachers can evaluate, students should too.