Here is my issue with Psalms and Proverbs. When you read them at this speed you really get a feel for the dominant themes that they share. It breaks down to this simple idea (with a few exceptions). The Psalmists seem to all be saying some form of "Hey God! Remember that we're the good guys and they are the bad guys. You should be blessing us and sending them to the fiery pits of hell." Even the psalms where the author admits to his (or the nation of Israel's) egregious sin, he is still wanting blessing for himself and punishment for those other people. His sins are somehow forgivable, but all those heathens don't get a second (or 532) chance to repent.
Herein lies my fundamental issue with the Psalms and Proverbs. They are both working from at best an incomplete and at worst a faulty understanding of who God is and how he works. This is made obvious by the Gospels, but it's also made pretty obvious by God's original covenant with humanity. He told Abram that he would be blessed to be a blessing, that all nations would be blessed because of his relationship with God.
It is made plain in the life, death, and resurrection of Jesus, that God is not about blessing the good people and punishing the bad people. In part, this is because there are not good and bad people, there are just people. God, as made clear by Jesus, is about redeeming, restoring, and transforming the lives of all people. Unfortunately not everyone accepts and embraces this gift of salvation, but it is intended for and made available to all people. God's desire is that all of humanity be saved through the redeeming work of the Cross.
But this is also what helps me appreciate the Psalms. Despite the misinformation, despite the petty vindictiveness, despite the unapologetic nationalism, when a person cries out to God, when any human seeks an audience with the Creator, regardless of the their race, nationality, theology, or mood, God makes himself available. He listens. He cares. He is moved, and he responds. This to me is the hope of the Psalms. Even when we are idiots and misunderstand God, even when our prayers are selfish and sometimes downright evil, even when have everything backwards, God loves us enough to enter into that mess and graciously sort us out. Because I'm not so vain as to suggest that I am beyond making mistakes like the Psalmists. I don't mean to suggest that my theology is perfect. This is why God's word is so amazing. He can take my frustration, disgust, and superiority and use it humble me and draw me closer to him. That is at least one thing that the Psalmists and I can agree on.