Here in the West, there are two divisions of Christian music: "Traditional Christian Music," including hymns and even really old stuff like Gregorian chants, and "Contemporary Christian Music," including rock, rap/hip-hop, and metal with specifically Christian lyrics. A lot of people have their personal favorites and get kind of nasty toward others who don't share their view. Let's look at some pros and cons of a prominent example from each division.
Hymns - Pros
Many hymns' lyrics are theological statements, which serve to teach the worshippers while they're worshipping, and solidify those truths in their minds.
Hymns lyrics are usually focused on God, not on the singer's emotional interactions with that God - causing some people to feel that hymns are more humble worship.
Hymns - Cons
Hymns are sometimes hard for modern people to relate to, since activities they reference and vocabulary they feature don't mesh with modern life - distracting the worshippers.
The hymns most often chosen to be sung are often...kind of...indistinguishable. Many have the exact same message, phrased very similarly.
Christian Rock - Pros
The fast beat and emphasized lyrics are powerful, evoking passion in the worshippers.
These songs are easy to learn, and are more likely to be played in other circumstances besides church (such as on a worshipper's iPod or in a Christian-owned business), meaning more worship time and more opportunity for unbelievers to hear them.
Christian Rock - Cons
For some people, the music itself creates a false emotional experience, turning worship of God into pseudo-idolatry. This is complicated by rock's roots in some very anti-Christian bands (although many hymns are set to tunes that were originaly bar songs, so depending on your perspective, rock's roots may be an non-issue).
Christian rock is often centered on the singers' emotional interactions with God instead of on God Himself, which is good for emphasizing relationship, but the frequency causes a loss of reverence.
My firm opinion is that neither division of Christian music is right or wrong - it is 100% a heart issue. The pros or cons of either division can completely disappear in an individual's case depending on their heart.
Ideally, we should be able to worship God no matter if the music playing is "our taste" or not - because if the music affects our ability to worship, then we're not truly worshipping God. But that certainly doesn't mean we can't have preferences!
The big thing is to absolutely not judge another believer for their Christian music preference - ever! (See Romans 14.) And I mean that for both sides of the spectrum! You don't know their heart, motivations, or reasoning.
Personally, I notice that we are told to sing to the Lord a new song, but that we are also given examples in the Psalms of old songs eternalized in Scripture. There is also quite a range of emotion in the Psalms, from joyous praises to gut-wrenching pleas. With all of this in mind, I personally enjoy and worship to songs from all across the spectrum - hymns and Christian metal are interwoven in my playlists.
Here's one final loop to throw into this issue: the doctrine of Common Grace. It gained prominence with the Protestant Reformation, and its basic idea is just that since God created everything, and that "every good and perfect gift is from above," anything good (and pure) in the world is a picture of God's goodness and is cause for giving glory to Him. This meant that everyday activities such as going to work were honoring to God, and that something like a painting, piece of technology, or song could be a cause to glorify God. For example, some of the great classical symphonies put me in a very worshipful mood, not because I'm idolizing the composer, but because I'm so in awe of the God who created the existance of beauty and created the human mind to create and appreciate it. Some people like this doctrine, others don't, and once again, I think it comes down to where your heart is at - people who cannot view it in that light shouldn't be judged, and neither should those who can.
What are your thoughts on this topic? Can you think of more pros or cons to either division? What type of Christian music is your favorite? How does common grace "sit" with you?
(Please remember to be considerate toward whatever view is opposite of yours, regardless of whether or not you share my view. I don't accept rudeness and judgmentalism even if I agree with the other points behind it.)