Except the r-rated action is exactly what the movie completely drops the ball on.
Your sci-fi movie's big climax is a shakycam fist-fight on a level platform? That's all you got? What's the point of having them in exo-suits if that doesn't even factor into the fight in any way? At least put them on a moving platform, or give me something unique.
Compare to Total Recall, which has like 7 different memorable action sequences, Elysium has got 1, maybe 2 if you're being real charitable.
It's incredibly forgettable as an action movie, and a major step-down from District 9 (gravity gun pig, exploding heads, alien hacker kid) in that department.