I'm sure many far more illustrious legal scholars will shortly provide detailed analyses of the judgment, so I will just quote two extracts here:
"Hildebrand v Hildebrand, in our judgment, is authority only as to the time when copies obtained unlawfully or clandestinely should be disclosed to a spouse. On that narrow point – what we have referred to as the 'rule in Hildebrand' – it was and remains good law. In other words, and we wish to emphasise this, it is and remains the obligation of a wife who has obtained access to her husband's documents unlawfully or clandestinely to disclose that fact promptly, either if asked by her husband's solicitors or at the latest and in any event when she serves her Questionnaire." (Paragraph 42)and:
"The rule in Hildebrand as we have stated it in paragraph  above was and remains good law. But that is all. The wider Hildebrand rules (which, we repeat, have no basis in anything decided by Waite J in Hildebrand v Hildebrand) are not good law.Some are already suggesting that the judgment and the demise of the Hildebrand rules will be a charter for parties to hide assets from the court, although the Court of Appeal seems to think that the parties who are victims of such behaviour already have sufficient remedies available. Only time will tell which argument is correct. Meanwhile, all lawyers involved in ancillary relief work will have to ensure that their advice complies with this important decision.
It follows that nothing in the so-called Hildebrand rules can be relied upon in justification of, or as providing a defence to, conduct which would otherwise be criminal or actionable (whether as a tort or in equity) nor as providing any reason why the relief (whether at law or in equity) which would otherwise be available should not be granted. More particularly it follows that neither the wives who purloin their husband's confidential documents nor the professional advisers who receive them (or copies of them) can plead the so-called Hildebrand rules in answer to a claim for relief..." (Paragraphs 120-121)