I used to think I'd want to try my hand at novelizations, but Greg's horror stories about the novelization business turned me off of that rather decisively.
As Greg said, the horror stories are more fun to tell, but I have as many pleasant movie novelizing experiences as horror stories. While it had a compressed timeframe (that wound up being unnecessary, as the movie's release was pushed ahead five months a day after I turned the book in), writing the Serenity
novelization was a joy and a privilege, the producers of Darkness Falls
were hugely helpful in providing me with backstory and script changes (they even showed me and my editor the changed ending so I could work it in), and for the third Resident Evil
movie I got carte blanche to expand on it and bridge the gap between the second and third films and also provide a subplot for a character from the second film who wasn't in the third due to the actor being unavailable.