It's not hard at all. It's just like changing the description or price. You just go in an change it, agree to the TOS, and save. Sure, you go through the two pages of the publishing process, but you don't have to change anything you don't want to.
I had to change the title of The Wife of Freedom (It was originally The Wh*re of Freedom - with an o where the * is. This made it impossible to list some places, and more difficult to get reviews because people didn't want that for a headline on their blogs, etc. Apple changed it to "The W***e of Freedom" which meant it could as easily be "The Whale Of Freedom" as anything. Plus "Wife" actually fit the story as well as anything, so I changed it.) There was no problem other than the old title and cover sticks in a few places, like Novelrank won't update to the new one.