Just installed one yesterday.
It's time consuming, but not that hard.
It took almost as long to remove the old fan as it did to install the new one.
Whoever installed the old fan had the hot and neutral wires reversed.
If you're getting a new fan, pay attention to whether it's flush mount or on a post that hangs from the ceiling and decide what will work for you.
I have some rooms where the ceiling angles in such a way where a flush mount wouldn't fit.