I liked it. It was a relatively lighthearted movie with fun action moments, which is what I've come to expect from the franchise. A new country was introduced alongside a few new characters who are easy to like and root for. We learn more about the world through this movie, and future characters are set up as well. Most importantly for me though, we get to see Rimuru and crew in action in a new narrative that feels very personal to many of the characters. As for specifics, there was a certain chase scene involving Rimuru and Ranga that I find memorable.
Like most other anime movies that follow TV anime, the Slime movie provides more of the TV series in a well animated, cinematic experience. I went in with those expectations and was very entertained!