I don't think anyone comes across as a villain, except possibly a couple of noted Australians. I am happy with this.
As far as the main characters are concerned, they gave everyone that they spoke to a fair say. I'm glad that Flower admitted to how he regretted some of the way he handled players and I hope that's mainly referring to the 'boot camp' which honestly seems ridiculous and cruel. It was meant to bring the players closer together but given what was happening 2-3 years later that obviously didn't happen.
My other thoughts in no particular order:
The interviews are very honest and personal, and it's great to hear a few stories I'd never heard before, like the anecdote about Bresnan punching Flower and the fond recollections of Jonathan Trott being weird.
Speaking of, the timeline more or less makes this a story about Trott, and the film is happy to frame it as such. The result is an ongoing theme of examining the mental health of the players and it's absolutely heartbreaking. The perspective offered at times from Finn, Panesar and even Pietersen are enlightening as well.
The aformetioned camp included an exercise that involved throwing things at a picture of Mitchell Johnson, which is hilarious. It's not clear if there are other pictures of australian players to throw things at, whether this is a designated exercise or just something a few england players did for fun, or anything really. It just happens and is never explained in any way.
I didn't mind the more 'abstract' shots of cricketers in water or fields and the like, I get what they were trying to do, but perhaps it could have been done with a bit more subtlety.
I didn't like some of the fakery. The worst is fake Ian Botham punditry that pretends he's stood on a pitch criticising the team in 2009, but it's clear been put in after the fact to act as a sort of in-universe narration. Additional Ian Botham punditry is never necessary.
They simplified a lot of the ins & outs. The bulk of the team stayed the same from 2009 to 2014, they rose up in 2009-11 and fell down in 2012-13, and it tells that story reasonably enough. But it feels weird to omit things like the 2012 series in the UAE, for instance.
What's annoying is that you suspect that they are constructing the 'story' around what they happen to have footage or interviews for, and while everything else has probably been cut for time, it makes the whole thing feel more artificial. Is there a crucial part of the story told by Collingwood, for example, while you had no reason to mention Chris Tremlett or Eoin Morgan? Or is it just that you happened to get an interview with the former?
Overall I think I forgive it for its flaws. It's got something important to say and the way we treat players is definitely a thing worth thinking about. It gets emotional at times and I appreciate the candidness of the interviews. It shouldn't really be seen as a documentary on cricketing history because it's a documentary about psychology and offers a look at how the sporting stories we watch might appear from the other side.