At the end of each school year, I have my students complete an evaluation of the course. My goal is for them to reflect (1) me, (2) the class, and (3) themselves. I find the evaluations extremely valuable. Scary at times, but valuable. This last year wasn't one of my best, and the evaluations showed that to me. But I also got feedback that showed it wasn't as bad as I might have feared (not that it was a horrible year, just that I think I wasn't at my peak). With so many students, the bulk of the evaluation is multiple choice, but there is space for students to write comments about particular questions, or comments about issues not raised in the questions. I use bubble-in sheets so I can scan them and export the results to a spreadsheet, which allows me to get in and really sort through the data.
Frank Noschese has me thinking that this year I need to give the evaluations a few times during the year.