Smallville tells the tale of a teenage Clark Kent in the days before he was Superman. It is the town where he came from where very strange things started happening with his arrival in a spaceship in the midst of a meteor storm of green rocks. Clark must deal with a variety of individuals given powers by the green rocks, keep his powers a secret, cope with his friendship with a young Lex Luthor, and balance the two girls in his life, Chloe and Lana. The show also shows us how Lex Luthor develops from a friend of Clark's and kinda-okay guy to (presumably) the villain who will plague Superman in his later years.
It does suck that Lex is gone, but I'm glad Lana left. She was a good character but I felt at the end of season 6 she should have remained dead and push Lex & Clark into real hatred.
By the way... isn't Clark suppose to be in college? When was the last time he was shown close to school?