The plot unfolds something like this: Lucio Fulci is directing a movie when he starts unraveling. He's seeing seeing murderous visions and has begun acting them out. How far will his delusions take him?
Yeah, he broke a cardinal rule: There's a rule in writing where you don't put yourself into your work. Some people brake this rule with great success (Kurt Vonnegut, Charlie Kaufman, R. Crumb, come to mind) but if you're not at the top of your game, it's not wise to break cardinal rules. And since Fulci was long past his prime (as he was no longer pairing with Dardano Sacchetti, the writer that gave him his best screenplays), he likely should have made this film about someone else in some other field.
The kills: Mostly footage from his other films.
Reasons to watch: If you're trying to see all the Fulci movies, this is one of them. It's not totally unbearable, but it's like watching a clip episode of your favorite TV show, with a Fabio Frizzi score. This is also an early iteration of the meta-horror genre.