Oh, my. It's amazing. It begins very slowly, and, unaccustomed as i am to the South African accent, i had to turn on the subtitles in order to understand what they were talking about.
In fact, for the first while it was boring. I said (to myself) "waste of money."
I'm not sure what the pivotal moment was, possibly when Wikus is exposed to the alien fuel. Whatever. Doesn't matter. Who cares. My jaw fell open and my eyes were glued to the screen for the rest of the film.