Being European and of a younger generation I had never heard of Mrs. Mitchell but I thought the documentary may be interesting because of the Watergate connection. Turns out it was rather exploitative of the current fashion of putting a woman center stage, even if her part in the story was at best marginal.
What I learned from this is that Mrs. Mitchell was a loudmouth who craved attention and who managed to turn a national scandal into personal drama. She was described as an alcoholic and, with due respect, she looked and sounded slightly intoxicated in a couple of interviews. The fact that her enemy was the despicable Nixon doesn't make her a heroine or a particularly palatable character... and what was that "My husband abandoned me in California!" Couldn't she organize her own transport instead of whining on the phone?
Finally, apart from her generic blabbering about her husband and Nixon doing "horrible things", these things always remained unspecified and I doubt she knew much about the real goings on, even if the biased narrative wants to make it look like Mrs. Mitchell was the direct responsibility of Nixon's downfall.