The film wasn't lacking in the slightest. Between the subtle verbal dialog hints dropped throughout that culminate perfectly into the final twist (really gives you that "oh shit" moment when it all clicks) to the nuance and complexity of communication that is delicately explored and conveyed as so to not drag on or rush, the film is very rewarding. Arrival did well because it was a cut above the dry, unoriginal, and mindless sci-fi films that have become a mainstay in the theaters. Taking time to develop its narrative rather than rush to large actions scenes or rely on long sequences of mundane exposition. Furthermore, the way the movie so seemlessly blends future and past together is an extraordinary feet in itself. Arrival is the type of film you have to want to watch and be invested in to enjoy. You can't just put it on as it won't babysit the viewer. If you don't find the subject material interesting, then I could understand why it would be a bore and not enjoyable, but to say it's lacking is a discredit to how well crafted the film truly is. However, As anything that is an art, a films value and quality to the viewer is subjective. Arrival managed to appeal to a lot of people for the aforementioned reasons, and therefor it did well with reviewers.