I agree with kihei. BlacKkKlansman is definitely not angry, and Lee is admirably restraint in his effort to highlight the racism in the country. The best part of the movie is definitely the eerie parallels between past and present, because they do not feel forced at all, and they really makes the audience think and reflect.
That said, I waver between a 6 and a 7 for this movie. While it is a timely and important movie, at times the pace feels dragged out and slow, as though there is not enough source material, and more content has to be added in order to make the story dramatic. Furthermore, the current news footage at the end is rather unnecessary, simply because the point is already made, and thus can feel heavy-handed. I am also not a fan of the cinematography, due to the asymmetry nature with a lot of the scenes, but that is just Lee's current personal style, which I never like to begin with. Honestly, he tries too hard to be fresh and different, but that is just a personal opinion.
Other than that, it is a well-made movie. The acting is great, and while I have been known to be critical of Adam Driver, who I am still not a fan of, he has really shown that he is a capable actor, as this is another string of performances that I like from him.
Even though I waver on the score, I would still recommend it, for the historical relevance. It is a movie of our times, and I would even say that in about a decade, it will be held as an example that reflects the current political and social climate of this decade.