If you are a huge fan of Demon Slayer, and want to see it on the big screen - a theater experience, then this is something you might want to watch. If you casually follow Demon Slayer, you probably shouldn't see this.
As literally EVERY SINGLE PIECE of advertisement and marketing information has thoroughly explained EXACTLY what this movie would be showing, there is absolutely zero reason for anyone to be surprised or feel "scammed" by what they saw.
This movie covers a short 5 minute recap of every season thus far, with the ending theme to each subsequent season playing over it; followed by Episode 11 of the Swordsmith Village Arc. The movie then finishes with the 1st Episode of the Hashira Training Arc - an early screening for a season that won't be out until Spring.
How exactly are people deciding to watch this movie without understanding the chronology of the anime? How are you not watching trailers or reading a simple excerpt from an article - or the literal movie description? You're upset that you're rewatching content you've already seen, yet it could just as likely be the case that you've skipped content and just got spoiled by watching this movie since you've failed to even check what the movie is about.
Please do yourselves a favor and utilize, at the very least, the tiniest bit of brain power you can muster, so that 1) You don't waste your precious time and money on a product you don't like, and 2) I don't lose brain cells having to read through these 1-star, angry reviews that shouldn't exist in the first place.
Media literacy. Learn it.