AP reported that the carrier said it was sending Spaccarelli a check for $850, along with $85 in court fees. While AT&T didn't comment on why it had given up on its promised appeal, it seems obvious to laypeople: it would cost more for AT&T to continue to fight than to simply pay out the relatively low award.
AT&T's Terms of Service prohibits subscribers from participating in class actions or seeking jury trials. The Supreme Court upheld those limitations last year. That leaves subscribers with only small claims court and arbitration as legal courses of action.
While Spaccarelli has always said that what he wanted was what he was signed up for --- unlimited service on AT&T's network. That's not going to happen, but in the wake of the original ruling in Spaccarelli's case, AT&T raised the limits at which it begins throttling and gave users solid thresholds instead of the vague "top 5 percent of users."
AT&T now begins throttling grandfathered unlimited data users (the company no longer sells that data plan) at 3GB for HSPA+ users, and 5GB for LTE users. AT&T didn't, of course, say that the change was the result of the earlier legal case.
While AT&T hasn't given Spaccarelli what he wanted --- truly unlimited data --- it has changed things for the better. In addition, Spaccarelli gets the $850 awarded to him, which is supposed to represent extra data charges through the end of his contract.