Lived in a JSM managed apartment for the 2009-2010 school year at the recommendation of the Tennant Union.
I didn't have any major problems. They had a quick and friendly maintenance staff. One time I came home at 3am and there was a maintenance guy fixing a leak that the tenants in the lower floors had complained about, so I know emergency maintenance gets done quickly as well.
On move-out I was charged a lot for cleaning, despite having cleaned some myself. I showed the pictures I had taken when I moved out to the leasing office manager. In the end they returned a fair amount of my deposit without having to complain to the Tennant Union. Expect to be charged for carpet cleaning (I think it says it in the lease) and always take move-in and move-out pictures.
Overall, one of the better large management companies on campus. People might know this because their apartments fill up fast. Consequently there is usually no room for negotiation with these guys. I will consider them for future apartments.