Black Panther is one of the best comic book films of all time, and while it has its flaws (which are few and far between), it's also the most important.
In production (technically) since 1992, Marvel's Black Panther has - much like the nation of Wakanda itself - long eluded the spotlight. Now that it's released however, there's little chance things will ever be the same. Ryan Coogler's superhero origin story is a testament to good storytelling, and while other Marvel films have made commentary in the past, Black Panther is a statement in and of itself, releasing within the context of a cinematic universe overwhelmingly dominated by straight, white Chrises, and in a milieu that has seen calls for better representation in popular culture increase by the day.
Black Panther is, then, important for a variety of different reasons. It has chronological significance for the MCU itself of course, but there's also a deeper significance that extends beyond the superhero genre itself, to the history of representation in its entirety on the big screen and how films approach history in their storytelling.
This is a key event in the genre as we know it, and while the film does have its flaws, it's by far one of the strongest Marvel features yet, and one True Believers cannot afford to miss.