I got two for when I'm gone on interviews. I give them to a friend in my classes, and she records the lectures for me. The classes that I do this for all have lecture slides that students print out before class, so that makes it easier to follow along. I need to record the lectures, though, because professors go into more depth than what is on the lecture slides.
Problems:
*for every hour of lecture, it takes me about three hours to decipher the tape. The quality isn't so great (and I have a good recorder), but it might be because my classes are all 100+ people. Still, even when the recorder is toward the front of the classroom, it is difficult to understand the tape.
*because I have the option of rewinding the tape, I end up writing down much more than I would if I were actually in class, pressed for time and trying to keep up with the professor. This makes it a bit overwhelming when I'm studying for exams, as I tend to (unnecessarily) write down the smallest details that are mentioned when listening to the tape.
Nonetheless, recording lectures saved me last quarter since I missed ~10 days of school.