Scott Aniol writes about Expression vs. Impression in worship (site no longer on line). While I do not agree with everything that he says about music in worship, his articles are always thoughtful. This one is especially helpful.
Some excerpts. . .
Music that is simply about emotion is self-centered and immodest. It is concerned more with the emotions themselves than in the object of the emotions. This kind of music allows the listener to revel in his feelings. This may not in itself be a problem, but when used for worship it is idolotry. We say we are worshiping God, and the text may have a lot of biblical content, but the form is actually prompting us to focus on ourselves and how we feel. Is is essentially what Edwards referred to when he described “passions” — purely physical emotions for their own sake.
What God desires in worship, on the other hand, is expressions of affection to Him. Worship music should be less about what I feel and more about who God is. God does not want to hear, “I fee this way, and I feel that way.” He wants to hear about Himself, and the acts of expressing affection demonstrate what we are feeling towards Him much better than if we tried to tell Him with words.
I’m not sure that our “acts of expressing affection” toward God can’t include a statement of how we feel about God. David certainly gives verbal expression to his feelings for God in the Psalms. But the focus of our worship should be on God Himself rather than on our feelings about Him.