Finally caught this last night, it felt like 110 minutes of "Last episode on Dr. Strange..."
They really needed at least another 15 or 20 minutes in there to make it possible to give a a shit about the characters, as it was it felt like they just jumped from scene to scene to convey to rough outline of the narrative in the fastest possible form. There was absolutely no sense of the passage of time - did the movie take place over 3 months? 3 years? How long was Strange training in Nepal?
Acting was solid though, Swinton and Cumberbatch were both great (side note, but am I the only one who thought Cumberbatch's American accent sounded exactly like Hugh Laurie's in House? it was uncanny) although it felt kind of wasted with the rushed narrative. eg. The whole scene with Tilda Swinton's character dying was really well done, but totally lacked any emotional resonance because they hadn't bothered to take the time to make us feel attached to her as a character. Same with all of the other characters, including the main villain, lacking any real backstory. Just felt like they were there to fill the roles "sidekick - mentor - comic relief - bad guy" etc.
On the upside, special effects were amazing. Overall I enjoyed it, and I'm not huge on superhero movies, but if they'd taken the time to flesh it out it could have been an awesome movie, instead of just a good one.