I guess if you were hoping that things would be getting better after the previous chapter, you will be disappointed. It seems to me in Genesis 4 that the downward spiral of sin is going faster. In this chapter we see murder, bigamy and pride. It seems that they (at least Adam and his kids) have a direct communication with God, yet this closeness does not change their sinful state.
One thing that confuses me is that I guess Cain married one of his sisters and that is not a big deal in their position. But he also makes the comment that whoever finds him will kill him. Who else is there? You pretty much know everyone. And it seems weird to me to think that he even has the state of thinking that there are other people out there who would kill him.
Lamech appears to not have been an upstanding individual. He appears to be the first polygamist and appears to think of himself as either more important to God than Cain or that he has enough strength to inflict more revenge than God Almighty.