Being both honest and blunt, I think it's bad.
Here are my reasons.
#1. It can retard progress very heavily.
Think about it. What is based on evolutionary biology, at least to a degree? Vaccine development. Genome mapping and comparison. Breeding. Taxonomy. Take such a rigid stance that evolution is wrong and a lot of very beneficial stuff goes out the window.
#2. It borders dangerously close of biblio-idolatry.
Think about it. We have two revelations from God. The universe He made and the book He inspired. We need to use both together. The universe teaches us about science and how it works, while the book teaches us about God Himself and morality and spirituality and whatnot. Trying to bend either one to cover both is folly. And saying that "it couldn't possibly have happened that way because the literal Bible says X" (whatever 'it' happens to be) is putting the Bible above the omnipotent God. It's putting a man-written book above God. THAT is specifically against the first Commandment. Even more than that, it is putting one specific interpretation of a man-written book about God above God Himself, while the universe God created that bears witness to Him according to the Bible says something else.
#3. It uses detestable methods.
Seriously. We're not supposed to bear false witness against our neighbor, and even our bitter, hated enemies are our neighbors. And even assuming that evolution is a bitter and hated enemy (which it isn't), Creationism is still bearing false witness. Groups and individuals like Kent Hovind, AiG, and the Discovery Institute are pumping out so much false information most people who oppose evolution don't even know what they are opposing, which is obvious from some of the posts here, in Crevo down in the open to all section, from other forums, from real life, from Chick Tracts, et cetera. Evolution is now the big enemy, which is solely responsible for everything wrong with the world, which contains everything that could possibly be in any way opposed to what a good, Bible-believing Christian should be (and good, Bible-believing Christians are of course only those who subscribe to the literal view above.) That's not much of an exaggeration, if it is one at all. Here I thought we were supposed to spread an example by showing truth and love, not disinformation, lies, hate, and other vile things.
#4. It's bad theology.
While not all Creationists subscribe to this idea, quite a few do. That idea is that if the Bible is not literally true, then God doesn't exist. This does back up to #2, putting the Bible ahead of God. God can use any device He sees fit. And being all-knowing, He could have chosen a device that would have the same words mean different things to different people in different times and still get the same message across to all of them. The Bible doesn't need to be literal to have God exist. Heck, God existed before the Bible was fully compiled, much less written. God does not depend on the Bible.
That leads into another point. God is not confined by the literal words of the Bible. Creationism seems to push Him into that tiny box. He could only have done what the literal words says and nothing else. Which is extremely untrue. God is God. God is not the Bible.
It also pits God's two revelations against each other. That is bad theology, aside from also being part of points 1 and 2.
#5. It defies a lot of common sense and needs a lot of outlandish claims besides the miracles detailed in the pages of the Bible.
1. It needs all scientists in the relevant areas of: biology, cosmology, astronomy, geology, paleontology, archaeology, nuclear physics, cultural anthropology, and several more to be wrong. Not just a little wrong, completely wrong. ALL of them.
2. It needs a huge number of miracles NOT in the Bible to work in the least.
3. All cultures have creation myths. Just because we believe one of the had the right God, everything they said MUST be 100% literally true? That's a little outlandish.
I could go on, but it's 5:30 when I'm writing this part (a.m.) and I don't want to strain my internal editor.
#6. It promotes bad thinking.
The Bible is not either all literally true or completely false.
If everything creationists have labeled as 'evolution' (which is waaaaaayyyyyyy more than just biological evolution) is wrong, Creationism is NOT automatically right. That, however, seems to be the belief.
#7. It drives people away from Christianity
I know several people personally, shenren, and a handful of folks down in crevo who used to be Creationists. A lot of the ones if Crevo and real life are now not even Christian anymore. After dealing with the previous 6 points, if it is found out that they are wrong, the effect on people's faith can be disastrous and drive them away. Since a lot of Creationism today is based around lies and false ideas, that means a lot of people are going to be in for a rude surprise.
#8. It is hypocritical.
Sure the Bible is literally true, just not the parts about a flat earth.
Sure the Bible is literally true, except for the stuff about a solid firmament.
Sure, science is evil and atheistic and gonna bring us all down, but Creationists'll enjoy its benefits right until they die.
Sure, God commanded truthfulness, but it's okay to lie about evolution.
Sure, Jesus preached understand, but it's fine to rail against and insult people for a stance most Creationists don't know anything about.
That is why I think Creationism is bad for Christianity and for Creationists. It's bad theology with a bad mindset, bad methods, erroneous goals, and lots of problems.
While it IS good that it gets people to question established science, the methods it uses, the conclusions it draws, the way it does about it, and its own attempt to dress itself up as science are misleading enough to offset any benefit that might derive from the questioning. Especially since almost all the 'questions' have been answered but are touted as having NOT been answered.
Metherion
Edit: And yes. I know I'm probably going to get blasted about most of these. But I just got done with finals, I'm finally home, and I've got 2 and 1/2 weeks to bicker about this before I gotta go back (assuming I don't pick up WoW.) So, I'm prepared. And I am not specifically referring to anyone in particular on this forum with any particular point except for the one line about shenren. This is an 'in general' posts.