The biggest and most immediate problem I had with Elysium is that it tries to do entirely too much for one film. Virtually every scene feels rushed to get to the next one so that they can cram the entire plot into 109 minutes. As a result, the film can't help but feel half baked and under-realized. Don't get me wrong, I would rather have a film that is smart and has something to say but falls short over a film that tries to achieve nothing and succeeds, but I wish they had jettisoned some of the side stories in this film and just focused things more on Max and his goal to get to Elysium.
The main side plot that ultimately served no purpose was the one involving Jodie Foster's character and her attempt to overthrow the government on Elysium. Early in the third act, this plot becomes wholly irrelevant and makes me wonder why they included it in the first place. Was it to give Foster something to do in the early scenes? Her character proved to be completely unnecessary and ultimately bogged down the whole film.
I was also bothered, to a lesser extent, by the heavy-handedness of the message behind the film. I understand the need for social commentary in a science fiction film, but this one felt a bit obvious in its messaging. It's not hard to sympathize with the sick & infirm, particularly when they are living in third class squalor, so many of the slow motion shots of crippled children felt gratuitous. I also felt almost no emotional connection to Max. Since his character is so late to the party on wanting to do the right thing, his "redemption" ended up feeling a bit hollow. I wanted the final moments of the film to be resonant and emotional, and they just weren't, ultimately leaving me a bit blah about the whole film.