I saw it last night in 2D IMAX, albeit not a proper IMAX screen. I think it's known as lieMAX. Anyway, the sound and cinematography was brilliant. What a gorgeous film. There were plenty of shots that would work well as a decent still, poster or print.
Story was a little slow. Overall I really enjoyed it.
I do think you're right, it was left open with numerous storylines left for prequels, sequels or side movies.
Definitely worth a watch in the cinema.