You will not find the schools in Edison (which has three zip codes) listed separately on most sites.
I will say that of the 340 closings in Edison since January 1, 2012:
154 of them have been in the 08817 zip code
47 in 08837 zip code
and 139 in 08820 zip code, so the area is selling well.
Great school.org is for parents etc to post their thoughts, and it's been my experience that more people will take time to post bad things, and those who think things are terrific never say so. (sort of like thinking your one vote won't mean anything so why bother to vote).
Besides that the last post about Edison High School was November 2011. There are lots of recent posts for the elementary schools .
Every 2 years, NJ Monthly Magazine posts the High School Rankings. The last one was in 2010.
Here's a link to the most recent rankings. Out of 322 high schools, Edison High ranked 177th.
ANY school is only as good as how hard the student works and what works best for that particular student.
You can also go to this site, and search school report cards (from the state of NJ) by name of school. Just click the first letter of the school you want and scroll to that school, then click the blue hyperlink to get the school statistics.