Superboy (Jon) suddenly turned good?

Not sure if I missed something reading both 2011 Teen Titans and 2011 Superboy, but I feel as if there really wasn’t much character development of Jon Lane Kent. His character did a complete 180 at the end of the series. Did I miss something other than a few people were nice to him and suddenly he is good?

No, you didn’t miss anything. The New 52 Jon Kent was a pretty inconsistent character.