It was quite draggy at the beginning towards the middle though, but I think it was meant to make us feel the slow exploration & desolation of space travel, hence putting us in the characters' shoes. Although rather different from “Gravity”. I like how the film focuses on relativity of time-space, giving a little more conflict and suspense as it shows character conflict in space and also in the meantime characters on Earth, increasing the tension, especially at the climax of the film.
Although did not watch it in IMAX (noo... :/ ), but there are still some visual spectacle in the film which really pushes the barrier of CGI. The music & score by Hans Zimmer is as usual awesome yet subtle throughout the film, as there are scenes in the film that utilises the absence of sound as it is in space.
I can see many people came out of the cinema halls, looking bewildered, confused, mindblown, and also checking their watches. Most probably checking the time (due to the long duration of the film) and maybe checking the date and year hahaha. :b