I asked Jack Stephenson, fresh from a fortnight at Personnel Today, what makes a good work experience placement. Here's his answer:
I believe that there are a few things that can make work experience good or bad; the first of these is the people who you work with. If you are working with people who you do not get on with, your time there won't be enjoyable. The second thing that is needed for good work experience is a good variety of things to do. If you are doing the same thing over and over again for two weeks then it will get repetitive and you won't want to go in anymore. The third thing that is needed for good work experience is something that you have an interest in, because if you aren't, then you won't want to work and won't have any passion for it.
I know some people from school who quit their work experience after one day as they enjoyed it so little.