As a white Australian I don't feel qualified to give an objective or informed review of this film. So these are just my impressions.
Overall, I liked it. Pretty much everything was done well (the writing, the acting, the period detail etc)
I don't normally like biographies, but I'd heard good things about Spike Lee, and have enjoyed Denzel Washington in everything I'm seen him in. I didn't know much about Malcolm X going in and deliberately didn't look anything up until afterwards to avoid "They got that bit wrong!" syndrome.
I was thus genuinely surprised by several aspects of the story, and found it very engaging. Stories about "Great Men" tend to be unconvincingly whitewashed and preachy, with all the difficult un-PC bits cut out or clearly marked as not part of the real message. While this film was definitely meant to preach a message, for the most part there was no difference in presentation between the stuff Malcolm X said that neither his older self or a modern audience would agree with, the stuff that we were presumably expected to agree with and be inspired by, and the stuff that Malcolm X believed but Spike Lee presumably doesn't such as the emphasis on Islam. This was a refreshing change from films like "Kinsey" or "Luther" (the last two "Great Man" films I've seen) For example, the characters in this film are often very sexist, including Malcolm X himself, but I didn't feel that the film was too bad in this regard beyond the usual Great Man male-centered storytelling, YMMV.
Even as someone very removed from the American civil rights struggle I found the film very inspiring and moving.
I found it a bit slow and confusing in parts, but I feel that way about most biographies, especially those of historic figures whose lives, words and context I'm presumed to know and resonate with more than I do. Looking Malcolm X up in Wikipedia afterwards the film seems reasonably accurate but I'm not in a position to judge.