Amidst all this, I think some here have forgotten that neither Masipa nor the Court of Appeal ruled that Pistorius knew/believed he was shooting at Steenkamp behind that door, rather than the mythical intruder claimed by Pistorius. In fact, both courts are agnostic as to the identity of the victim.
I am sure that Steenkamp's family - and, it seems, some people here - would have liked the courts to have found that the "intruder" story was a lie, and that Pistorius had knowingly targeted Steenkamp. But that's not what they found. And, in a very real sense, they had no need to make such a finding (and indeed to have done so could have made this a much more appealable case by the defence). All they had to show was that Pistorius knew it was a human being behind that door - whether he genuinely believed that human to be an intruder, or whether he knew it to be Steenkamp.
Personally, I think that the evidence and testimony all point very strongly to the conclusion that Pistorius never did genuinely think there was an intruder, and that he knew it was Steenkamp at whom he was firing his gun through the door. I think the evidence strongly suggests that Steenkamp ran into the bathroom and locked herself in the toilet with her phone, in order to put a physical barrier between her and a jealous/enraged Pistorius and in order to make a distress phone call (either to police or to family/frienpland). But that's all conjecture.