My son (as of today) is a rising 7th grader. He has been at NES since 4th grade.
Last year (09-10), there were some issues with a couple of the 5th grade teachers. However, I would say that we had a VERY positive experience. Ms. Salinas, Mr. Christian, and Ms. Devizen are fabulous teachers (I don't know the two new teachers on the team). My son still talks about them. This year, in 6th grade was also a positive experience. The 6th grade team works well together and are open/receptive to parents.
Next year, both 5th and 6th will no longer be rotating teachers (like a high school model--the class moves to the science teacher's room or the math teacher's room etc), and be self-contained. So one teacher for the day.