teacher evaluations, its a double edged bat'leth?

So we had our battery of teacher evaluations today and as i was filling out the 3rd one i wondered about whether it was teacher evaluations or assessments, now that may be a bit nitpicky but what we did was not give a grade or number score but gave our opinion about the capabilities of these teachers. one thing i have learned, especially being the biology teacher, is that opinions are like butts, everyone has one so dont think you are special because of yours. so what real worth are these reports, i understand the theory behind the idea that it is to give feed back so that a teacher can see from the students perspective how they are doing and improve where they can, but REALLY, i think that my 2 years of teaching high school has taught me a few lessons and one is that a good teacher knows that being the popular teacher doesn't mean that you are doing things the best on the acedemic front. so what does that mean...well i think that these tests SHOULD be done unbaised but if the teacher has spent the semester returning C grades to you (whether its because you are slacking or they are being hard on you) the view on that teacher will come up at review time.

i'm not saying that we shouldn't because some people need to know how out in left field they are but maybe another method could be devised.