The amount of Marvel movies that have come out over a short period of time has led to what people refer to as, the Marvel Formula. This means that pretty much most of the movies follow a formula that is successful, but still is formulaic in nature. This movie blows all of that out of the water and decides it actually wants to get creative.
Doctor Strange is the most creative movie ever made in the Marvel movie timeline so far. It's the best one by a mile because of the denial of that Marvel formula. Doctor Strange is an origin story, and people usually don't like those, but you have to go see this movie. It packs in the action and makes you believe in this new world, ironic since there have been over 10 Marvel movies already.
The way that Doctor Strange decided to depict itself was really out of the box thinking. From the character to the way the movie was made, it all came from a place of pure creative intent. Some writing the movie off as an average one with visuals to sell the tickets, but I argue that the movie is fantastic overall. The story was great, easy to follow and complicated enough to enjoy what was happening on screen. The depth that this movie provides is deeper than some might give it credit for, if you dig you wont be disappointed.
It's hard to talk about the movie without giving away pieces of it and spoiling it. So I'll end with this: Doctor Strange is my Guardians of the Galaxy, in that it is the Best Marvel movie made to date.