According to the Bible, we all fall short of God's standards. The law condemns all of us. So by these standards, none of us are good. Yet, as ViaCrusis said, we have been offered justification. Jesus took our sin on Himself, and so by substitution, God looks on the saved in the same way He looks at Christ.
The only opinion that really matters to me is God's. If He says something, I match my thinking to it. So really, the answer is both yes and no. No, I am not a good person, because I fail to obey God's laws, and I sin regularly. But God looks on me as if I am blameless, and it would be insulting to what Christ did for me to continue to see myself as a dirty, no good sinner. I have been made clean.
Sometimes, a simple answer just doesn't cut it.