What do you think of your previous boss?
This is a potential banana skin of a question. If you hated your previous boss and let your interviewer know, you risk having it reflect badly on you. Generally, speaking negatively, regardless of subject, will create a negative impression of you. Especially when talking to relative strangers. Speaking negatively could also indicate a sense of insubordination towards your superiors. This will not be a characteristic the interviewers will be looking for. Therefore, it is highly advisable to be positive of your previous employer, or failing that, at least neutral.
More often than not, there will be positive aspects to most of the people we meet. When tackling this question, the interviewer is not necessarily interested in your personal relationship, or your personal feelings of your last boss. Instead, they will be gauging how perceptive you are to other people’s qualities. For example you could say, "My last employer had exceptional communications skills, I was particularly impressed how he managed to defuse irate customers and hope I have managed to learn from that. He was also very approachable and I believe any member of staff would have felt comfortable to go to him with a problem." This shows your ability to see positive characteristics in people and learn from them. It is also evidence that you are willing to improve yourself and actively try to do so.
In answering this question positively, you are enforcing a positive projection of yourself. Although you are directly speaking about someone else, you are proving that you have the ability to see and identify key characteristics in other people. This will be interpreted in a way that it will be assumed if you can see this in your superiors, then you will be able to do it with those below you. With subordinates, using this skill you will be able to positively influence behaviour and increase productivity.