Dr. Strange was interesting, entertaining and original. Like most Marvel movies, they were willing to take some chances and eschew trite formulas from the past.
I knew Dr. Strange mainly from reading a reprint of the original story, but never got into it that much. Magic characters from Harry Potter on down are kind of flawed because nobody really knows what their powers are. Here's how it works. The good guy uses his spell to stop a bad magician.
"Oh yeah? Well let's see how you handle my BAD GUY SPELL! Aluminium Recyclum! Bwahaha!"
"Hoho! Too bad for you that I have an even more powerful GOOD GUY SPELL! Sanctimonium barfitosis!"
...and so on. After a point we need a commentator to come in and tell as whether the good magician has won or lost. It is hard to create suspense because the spell powers are so poorly defined that we just can't get excited by any threat they may pose because there is always a potential antidote spell.
At any rate, the movie tells the story of Dr. Strange's strange journey from being an arrogant but talented surgeon, to losing his ability due to a horrific car wreck, and his search for meaning in mystery religions in Asia. In the comics, Dr. Strange was actually a psychedelic hippie, even before the Beatles found Guru Maharishi Yogi. At any rate, in this movie he is able to find self help gurus beyond compare at a mysterious temple in Tibet.
Dr. Strange loves parallel universes. Suffice it to say that the rules for parallel universes are as complicated as Einstein's theory of Relativity and the NFL rule book. So you really can't figure out how all this works, you just have to wait for one of the characters to explain in more simple terms what is going on.
I like that in Marvel movies the characters are not one sided. It's hard to know whether they are evil or good, or indeed whether they are capable of knowing the difference or making a choice. We can't even be totally sure that Dr Strange is a good guy. Maybe he's not.
Can evil magic be used for good? Or is it always evil, and if so, why? What makes it evil. These are things that Dr Strange has to ask, with his genius for scholarship and his affinity for magic. His senior fellow sorcerers and teachers also struggle to achieve a balance between good and evil. On that level, the characters are very believable.