This is it. The 6-page document legally analyzing the "backstop" agreement on EU/NI/UK trade, the one that May's government would do almost anything to avoid releasing. After repeated and increasingly growly insistences by an irritated Parliament, they gave in and let it out. (HTML cover page linking to PDF of the full document.)
So what's it say? It says that, though the backstop is declared to be temporary, that's temporary only on the basis of it being succeeded by a permanent agreement, which the parties are bound to proceed towards in good faith.
But since there is no perceivable way to reconcile the fundamentally conflicting imperatives on the Irish border question, at least not one better than the jury-rigged backstop, that points to a particular form of legal and administrative hell:
1) The backstop will go on applying indefinitely, possibly permanently, despite the fact that nobody likes it and it was accepted only because it'd be temporary;
2) The EU and UK will be, because of the "good faith" clause, bound to keep on negotiating actively, despite the fact that neither's desired position is even remotely acceptable to the other. They could well just sit there and make the same futile points over and over again. This could go on ... possibly forever.
Of course, there is a way out, though the Attorney General is too polite to specify it, saying only that this is a political question. That way out is: no Brexit.