The book is always better. That is the immortal phrase uttered by THAT a-hole in your friend group whenever adaptations of famous novels, comic books, or anything else are discussed.
And it isn't hard to see why, as stories are typically made for the story format they are for a very good reason, and thus adapting it into a different form is likely going to take that aspect of the story away.
For instance, if you were to make a Bioshock film (which they tried and failed to do) you still get the good story of Andrew Ryan and the world of Rapture, but you lose the player interactivity and game trope context that makes the "would you kindly" twist so effective.
But sometimes abandoning the source material is for the best for all involved. Whether because the movie we ended up getting was awesome on its own, or because the source material deserved to be abandoned, there are some films out there completely abandoning what they were adapting, only to be much better off for it.
From the depths of darkness and madness did rise John Tibbetts. His ancient will arising into this new world, beholding a universe that lacks his beauty. Now he shall spread the gospel of his terror by...talking about movies and video games on a British geek site.