It was promoted as the princess at her "most candid, natural and charismatic".
There was plenty of emotional music, news clips, quotes from close friends and of course the tapes she'd recorded with her voice coach.
It was also brutally raw in parts.
And as it was being aired The Sun newspaper was reporting more salacious details that it says came from a BBC cameraman.
The Sun reports: "Princess Diana claimed she once spied on Prince Charles on the toilet having 'phone sex talk' with his now wife Camilla Parker Bowles."
The newspaper said Princess Diana thought Camilla, Duchess of Cornwall was the "raunchier of the two" after listening in on some of her husband's phone calls to his mistress.
The claims emerged in 12 hours of footage filmed by a handpicked BBC cameraman five months before her death in 1997.
But these are not the tapes that provided the basis for the Channel 4 documentary that has been debated very publicly for the past few weeks.
Princess Diana sat down with her voice coach Peter Settelen in the early 1990s and poured out her heart as he coached her to begin finding her own voice and preparing for the revealing and damning interviews that would come.
The highlights (if you can call them that) include:
- Prince Charles was an awkward wooer of Princess Di and was "all over her like a rash" and would "ring me up every day for a week and then wouldn't speak to me for three. Very odd"
- The couple met only 13 times before they were married
- Princess Diana went to the Queen sobbing and asking for help but got no support
- Princess Diana was traumatised during a post-engagement TV interview when they were asked if they were in love and Prince Charles responded, "whatever love means"
- She had fallen deeply in love with someone else by 1985 (believed to be bodyguard Barry Mannakee) and was devastated and suspicious when he was killed in a motorbike accident three weeks after being forced to leave the palace
- She had confirmation the affair with Camilla, Duchess of Cornwall was going on within five years of her marriage to Prince Charles
Watching the 90-minute documentary felt like an invasion of privacy and Princess Diana's brother Earl Spencer had pleaded with Channel 4 not to broadcast it.
But Channel 4 said the material was of historical importance.
There is no doubt they are damaging to the monarchy and especially Prince Charles — the future king.
He comes across as cruel in his emotional approach and unloving.
On social media people appeared split — some outraged by the immorality of Channel 4 broadcasting it and by the voice coach (a former Coronation Street actor) making the tapes available.
Others were spellbound all over again by a charming woman who appeared to be a victim looking for empathy.
We don't know what kind of money changed hands for these tapes.
And after all the fuss over the past few weeks there was no bombshell.
In fact parts of the tapes had been broadcast more than a decade ago in the US but this was the first time they were being seen in Britain.
Princess Diana said they were a "great team" publicly in the way they carried out their duties and she had wanted more than anything for the marriage to survive.
But it faltered quickly and her death 20 years ago this month was a devastating time for the royal family and the public who mourned her.
The anniversary was always going to be a moment to relive the best and worst of the royal fairytale.
This documentary falls into the latter.