TL;DR: Basically a 1.5-hour long version of the show, with all the jokes and fanservice you'd expect from Konosuba!
The Good - The humor is on point, exactly the same quality as the show. Kazuma's antics are entertaining as always, Megumin gets plenty of fanservice, Yunyun gets a bit more screentime, and even the new villain is memorable. The interactions between the characters were a goldmine of laughs for me. Story-wise, it's a simple story about the gang visiting Megumin and Yunyun's hometown. Nothing special, but no one watches Konosuba for the plot, amirite? ;)
The Bad: Since the movie is basically just an extended episode, the animation was lacking in quite a few places, which is even more noticeable this time since it's supposed to be a movie. Background characters sometimes barely have a face. True to the spirit of Megumin, they seemed to put more budget into just the explosions, which looked pretty good.
Overall score: 8/10 - If you liked the show and don't expect the movie to go above and beyond the show's quality, then this will be a great watch. If you didn't like the show, why are you even reading this review? Go watch something else, pleb. :P