In most Catholic communities there is debate over the worship music. With the range of music available for churches it’s no wonder that there are differing opinions. The vast range of tastes reflects the vast range of music types.

What we must do is trying to choose liturgical music is sort out some basic questions: First of all, what is music at Mass for? It is not to make us feel good or even feel holy. It is to give us voice to worship God. There are secondary functions: it may inspire us. It may help us to express our love for God and our desire to serve him. It may build esprit de corps. It may encourage and uplift us. However, all of these functions, while worthy, are secondary. First of all a hymn is supposed to give us the words and music to worship the Almighty.
If this is correct, then we can therefore judge whether a hymn is successful in doing this. A few basic questions can be asked: First; are the words of the hymn addressed to God as words of worship? “Praise my Soul the King of heaven” works. “We the people are gathering now etc.” doesn’t. There are some devotional hymns that express personal devotion and work well, but they are better suited as communion or offertory hymns.
Many of the contemporary hymns are faulty in other ways. Many of them quote Scripture. This is worthy in some ways, but it becomes absurd when it is turned into a hymn. “I am the Bread of Life, he who comes to me shall not hunger. I the Lord of sea and sky. I have heard my peoples cry.” These are the words to a popular worship song, but why does it makes sense to sing the words that God speaks to the prophet or words Jesus said to us back to God? This is not worship, it is a musical Bible meditation. 
These type of Scripture quotation hymns are often also what I call ‘comfort hymns’. “When you walk through the darkness I will will be with you. Be not afraid. I will bear you up on eagle’s wings. I will always hold you in the hollow of my hand. etc etc.” While these are wonderful Biblical promises, again, they are not hymns of worship directed toward God. They are hymns of comfort directed towards us.
This leads me to the final problem with many of the contemporary worship songs. They are frequently about us, the people of God and our mission in the world. “We can make a difference. We can make a difference, yes we can.” While there is certainly room for some hymns to be about our mission in the world (especially as a recessional hymn) when they are all about us, the community and our mission to change the world it changes divine worship into a sort of pep rally. 
When I speak on this topic I am often accused of elitism or snobbery or ‘being Anglican’. Perhaps some of this is true. I would simply counter that I am only trying to do my job, that I am supposed to know something about worship, and I don’t pretend to be an total expert in the field, but I should know a little bit and try to apply it.