Sherry at Stay of Execution has a phenomenal post (and I don't think I throw the word "phenomenal" around all that freely) about what makes a good law professor. I agree with most of what she has to say, and she says it very well. Despite the fact that I don't think I can do a better job than she's done, here's my take on it (and apologies that I'm stealing the title of her post):

What I Want In A Law Professor

You are brilliant, even though you may or may not care if we realize it. I'm impressed if you wrote the casebook, but even if you didn't, you've read the casebook. You may have taught this course three dozen times already, but you still care about the subject, and it still feels fresh to you. You haven't memorized your lectures. Calling on people isn't a way to give yourself a break from talking, or thinking. You actually listen to what the students say and try to answer our questions. Even better, you use the very best questions to springboard into different areas you may not have even planned on talking about, but somehow they've become relevant. You never say, "this discussion has gotten really fascinating, but I'm going to stop it right in the middle and move on to something extremely boring." In fact, you never even think that. You have no patience for students who make the classroom anything other than a collegial atmosphere, and you don't hesitate to do what you can to eliminate any distractions they're causing. You acknowledge when material is confusing. You admit when you've made a mistake, or misspoken. You double-check any math you do on the blackboard, but don't fight it when twelve students tell you you've added wrong. You don't tell us we can learn the subject better from a commercial study guide, even if you think it might be true. You tell us just enough about who you are and what you've done that we're in awe and want to know more, but not so much that we feel like we're watching an episode of A&E Biography. You have very little patience for students who aren't trying. You have more patience for students who actually are. Even if you don't remember our names, you remember what we've said, the questions we've asked, and make us feel like you know more about us than perhaps you really do, because, to you, getting through to each student really is important. You read the newspaper and bring up relevant issues in the news. Sometimes you bring up irrelevant issues in the news, just because you think they're interesting, and, because you're brilliant, you have something interesting to say about them. You attempt to be funny, whether or not you succeed. It's the effort that counts. You don't assign reading that you don't care if we read. You don't assign reading that you're sure you won't get to. You ask hard questions, but you throw us enough rope that we can find our way back if we get lost on the way to an answer. You smile. Your exam is hard, but fair. You take the grading process seriously. You aren't afraid to e-mail us about things you think we might be interested in. You want students to come to you, but you realize that sometimes we're intimidated, and so you try to make it easier, and genuinely encourage interaction. You answer e-mails. You don't complain in class about having to have office hours. You love your job. You have a good heart. You care.