I saw it last night! First time in IMAX, second time overall. I picked up a lot more stuff this time. Knowing now how all the stories are intertwined and not always in order.
For example, showing a set from the plane's point of view, you might see them fly over a trawler with guys bailing out. But you do not immediately connect that to the guys that boarded it to escape 20 minutes ago, when it was onshore. But then a scene or two later you see them from the water point of view. All well done.
Yeah, it wasn't immediately clear that the events weren't happening at the same time. But it made for a great "ah-ha" moment when it conected the stories.