If you use a rubric with young students it is imporant to make it with them. Explain what each of the sections means and what each box is for. That may sound silly, but as a young student a rubric just looks like a lot of boxes with words in them. Also its important to use language and words that the students can understand. If you use too big of words they will not know what you expect of them. I loved the idea of making the rubrics with your class so they know what exactly they mean, and what it takes to write a good paper, or whatever the assignment is.
I still have some reservations about rubrics, but I can also see how they can be helpful. If rubrics are used correctly I think they could be a great tool in the classroom because then the students know exactly what the teacher expects of them and exactly what they need to do to get a good grade.