(SPOILER FREE REVIEW)
So, of course you need to have seen the first season before going in for this movie, but definitely don't expect the same tone or high quality of character development and life of that original first season.
The animation is excellent other than some of the 3D animation of the main villains body being very hard to look at (not from gore, it just looks bad). The music is very good, but it lacks some of what made the music for the original show so good, and the tracks that did carry over were remixed to hell. The voices seemed to be mixed improperly with all other audio and were very loud compared to any others sounds in the movie. Zenitsu is mostly ignored and was only brought out for a "haha funny" a couple times, he was basically dropped off (along with Nezuko) for the final fourth of the film. Inosuke really shines in this however, with great dialogue, new moves, and some development to his character carrying over from the original show. Tanjiro does great for the first half or so, then drops off character wise, and his battles with anyone other than his own psyche are definitely not a great show of who he is character and ability-wise. Rengoku is great, hands down, but he feels like the main character of this and doesn't really have the development to back it up, what makes you like him is mostly just how he and Tanjiro interact and how badass he is whenever his blade is drawn (or not). And at the end of the day the best part was the very end of the movie.
The biggest issue with this however, is that it is very clunky. You can tell that these just feel like episodes attached together with some light filler, rather than a coherent beginning to end story. Characters drop off, the main villain is gimmicky and is defeated half an hour before the movie ends, and personality wise he is much like a cool bookcover with blank pages inside. Progression of characters and plot is very stunted and leaves you a bit disoriented as things go back and forth. Episodes and weekly chapters do NOT translate well into feature length films. I cannot entirely blame the original writer nor the group that made this film for this, but if they insisted on making this into a film they could have made an effort to fill plotholes and make the story more coherent in film form... but they didn't.
I definitely still like the movie alot, but it definitely has it's issues. I cried a few times, but that doesn't mean the movie is a masterpiece, it just means it had emotional moments. This movie is GOOD, but it isn't great. I give it a 3/5. See the movie for yourself and make your own judgment.