Just watched the movie. The Demon Slayer movies really are just regular Demon Slayer episodes but with the CGI and effects turned up to 11.
The animation isn't any better outside of having 10x more slow motion shots, and 10x more CGI explosions. You'd expect better from them for the finale, but I guess more of the same is what we're getting, and thats okay if you're already happy with what the anime has been giving us.
Though don't be tricked by people calling it a cinematic masterpiece. That's just the usual cinema bias that you get because of watching something on a larger screen with surround sound (The reason why people called Dandadan and Bleach "movie quality" when the early screenings happened), it looks the same as it always did besides the massive panning shots of large CGI areas, and the explosion/effects violating your eyes the entire time.