I only started following this right before the trial started, and I read a few articles and thought the state is going to have a really hard time proving premeditation and murder -- but of course there was not much information out at the time. Here's my progression of how I have swayed from "not guilty" to "definitely guilty" to "not guilty" to "I don't know:
Burger
Then the state put on their first witness -Burger and I thought "That's it. He's so guilty; his goose is cooked." But then Roux poked some pretty significant holes in her account when he compared it to her prior written statement, and she was so stubbornly resistant to conceding even reasonable points, that I began to wonder if she was maybe a little too gung ho for the prosecution. She stated that she thought OP was lying and by implication guilty, so I wondered if she was(perhaps even unintentionally) framing her testimony in biased manner (adding embellishments about the screams, adding the detail that she heard a man and woman screaming at the same time, etc).
At that time, Roux was merely suggesting that the shots she heard might have been the cricket bat hitting the door - a suggestion that I initially dismissed out of hand, as I could not conceive that the two could sound the same or even similar enough to be confused.
Johnson
Then Johnson also seemed compelling and believable when Nel was questioning him. But again Roux cast doubt on his testimony as well - he changed the number of shots he heard from his initial statements, changed his description of the screams, and also added a man and woman screaming or yelling at the same time.
So at that point, I have some doubts about their testimony -- not their whole testimony, but certain parts that were changed from their initial statements. Johnson was more credible to me simply because he at least seemed willing to consider that he misinterpreted the sounds or the screams.
Van der Merwe
Then Van der Merwe got on the stand and we hear that she heard "loud talking" by a female on and off from 2-3 and then 4 bangs around 3:00. That seemed to corroborate some of the Burger/Johnson testimony and also added the implication of an argument between OP and Reeva leading up to the gunshots. At that point, we have no point of reference for the two sets of sounds, so it seems like Merwe is describing the same shots the Burgers heard. But then she says she mistook OP's loud crying for the sounds of a female. Hmmm. I started to wonder if it's possible OP's screams really did sound like a woman ...at least it now seems possible.
Merwe's testimony is a bit confusing because of the translation issues IMO but listening closely it's clear that she does not know where the "loud talking" was coming from and she didn't hear the other side, so it's not clear that it was even an argument (maybe one side of a phone call argument?)
Dr Stipp
Dr Stipp's testimony was crucial because it gave context to the two sets of sounds and for the first time we hear from an actual witness that the gunshots and cricket bat both sounded like gunshots - and that those sounds were separated by several minutes.
He was also on the scene within minutes and can give a direct description of Oscar's appearance and demeanor as well as Reeva's condition
He says he sees the light on after the shots and about the time the screaming started - "several moments" after the 3 shots he heard, as he described it. On the face of it, this is at least consistent with OP's own account.
Vermeulen and Mangena
Together these two experts testify that the gunshots were before the bat strikes, OP was on his stumps when he shot through the door, and OP was standing at a farther distance and at an angle from the door when he shot through it.
I know there are disagreements about what they really meant, but IMO this was the substance of their testimony.
Mrs Stipp
She also heard two sets of noises several minutes apart and also believed both sounds were gunshots - they sounded the same. She says she hears man and woman screaming - but there's still that doubt in my mind because of Merwe's misidentification of female/male loud crying. Taken together with the expert testimony, it at least seems possible that it could have been Oscar crying/screaming/yelling because the forensics suggest that Reeva would have been incapacitated. (I know, I know, most of you disagree, but I'm just laying out my thinking and the evolution of my opinion)
Phone/Data Guy
Messages indicated that there were some problems and this probably wasn't the most healthy relationship, but there were also many messages that indicated that the two were very fond of each other and still in the grip of a new romantic relationship.
The messages also indicated that Oscar was not jealous about Reeva visiting her ex-bf soon before the incident. That was a big deal to me. While there did seem to be some petty jealousy on Oscar's part (Reeva talking to some guy when Oscar was ready to leave and touching his arm, etc), there's nothing at all to indicate that he was consumed with jealousy or that he acted out violently as a result.
So by the conclusion of the state's case, in my mind there is already reasonable doubt about whether the witnesses heard Reeva screaming between the two sets of loud bangs. And if there's reasonable doubt about Reeva screaming and no clear jealousy motive, then there's really no case for premeditation.
Oscar Pistorius
I believed that it would be somewhat smooth sailing for OP after the state finished its case in chief, but OP has proved to be a horrible witness. Not only is he a bad witness, who IMO is easily confused and easily led - his defense was undermined by his use of "accident" and his (obvious IMO) refusal to ever use the words "intent" or "deliberate" even though that's what he was describing. It just confused everything.
Then Nel brings these pictures back out that would really obliterate Oscar's account if we could confidently accept that they were actually depictions of the crime scene as the police initially found it (untouched).
OP also made some mistakes that are concerning - I can't recall exactly what they were but there were a couple that really made me question whether he's hiding something.
Other issues of concern: The food in Reeva's stomach and what appears to be an improbability that her last meal was at 7:30 as Oscar reports. Another issue is the addition of the assertion that Reeva was awake and talking to him as he was getting the fans. Another issue - the whole layout of their bedroom and all the maneuvers OP would have had to go through to get from the point of first hearing the sound in the bathroom until the point that he is at the corner of the bathroom with his gun pointed at the toilet.
At this point, I am keeping an open mind and I'm anxious to hear more evidence that might instill a more abiding conclusion in my mind.