I've seen every animated film Marvel and Lion's Gate has done. "Ultimate Avengers" and it's sequel were good, but not great. "Iron Man" was just plain bad. But with their fourth film, they actually get it right.
"Dr. Strange" is an origin movie and as such suffers from the plight of most origin films. Crams a bit too much into one film. What this does is the final fight is a bit rushed, though not anti-climatic.
The movie is very well written and has a solid cast. Their are changes from the comics, but when hasn't their been changes from comic to movie? In this film, the changes don't hurt. The way magic is used is more like martial arts then what we see in the comic. This gives the feel of wuxia film. Magicians use a lot of magic swords in their fighting. Which actually works better then it sounds.
The only downside to the film is the backstory with Strange and his sister. That is riddled with plots holes but is brief enough that it doesn't drag the rest of the film down.
I highly recommend this film.