The changes to Dr. Strange's character make him a twin for Robert Downey Jr.'s snarky Tony Stark. That's faithful for pre-magic Dr. Strange, not so much for post-magical-training Dr. Strange, possibly early Marvel's least quippy hero -- even Reed Richards (or Sue Storm, for that matter) got off more zingers than Dr. Strange in the 1960's. Created by writer-artist Steve 'Spider-man' Ditko, Dr. Strange's non-quippy gravitas probably makes him the Marvel character who would most benefit from a trade to DC Comics for, say, the Legion of Super-heroes.
Benedict Cumberbatch is fine as Dr. Strange, and Chiwetel Ejiofor does nice work as a seriously reworked Mordo. Mads Mikkelsen plays the least interesting Marvel Movie villain since Mickey Rourke and Sam Rockwell in Iron Man 2. Rachel McAdams is stuck playing Natalie Portman in the Thor movies, only moreso.
The movie's visuals fail spectacularly at the end even as they also succeed admirably in translating Ditko's surreal comic-book visuals of the Dark Dimension into the movie world. To say that the visual redesign of Dr. Strange's greatest foe is regrettable is about the most praise I can offer. The poor bugger has been biggie-sized into a giant floating head that looks an awful lot like what would happen if you painted the Tron visuals for the Master Control Program onto an accordion.
As to the white-washing in regards to Asians... yep, one of Marvel's first prominent, 'good' Asian characters is no more. Doc's mentor, the ancient Asian known only as the Ancient One, is now the surprisingly spry Tilda Swinton, a.k.a. The Whitest Actress Ever. And the other tweaks made to the Ancient One's character don't help much either.
In other areas, the magic training Strange endures now has all the length and rigor of selecting icons off a computer screen. Really, it makes the Harry Potterverse seem like a world teeming with educational rigor by comparison. Doctor Strange just has to make funky Kung Fu moves -- no pronouncement of spells required. And the mystical doodad Strange and friends need to travel through space-time? It's there to be dropped at a crucial moment, as these things always are. Lightly recommended.