The key parts, in my opinion, are these:
In paragraph 50:
In all circumstances, the United Kingdom will continue to ensure the same unfettered access for Northern Ireland's businesses to the whole of the United Kingdom internal market.
In paragraph 49:
The United Kingdom remains committed to protecting North-South cooperation and to its guarantee of avoiding a hard border. Any future arrangements must be compatible with these overarching requirements. The United Kingdom's intention is to achieve these objectives through the overall EU-UK relationship. Should this not be possible, the United Kingdom will propose specific solutions to address the unique circumstances of the island of Ireland. In the absence of agreed solutions, the United Kingdom will maintain full alignment with those rules of the Internal Market and the Customs Union which, now or in the future, support North-South cooperation, the all-island economy and the protection of the 1998 Agreement.
Paragraph 50 I assume satisfies the DUP that Northern Ireland won't be detached from the UK but paragraph 49 may come back to haunt them for several reasons. It puts the onus on the UK government to come up with "specific solutions" to the border problem. But if this is some sort of invisible, frictionless border one wonders why it can't be applied to the border between NI and the UK. The Irish may say you have a solution that could work that still allows "unfettered access" for Northern Ireland to the UK.
The phrase "in the absence of agreed solutions" means the Irish have only to refuse agreement and we will be committed to maintaining "full alignment" with the EU internal market and customs union rules that, "now or in the future, support North-South cooperation, the all-island economy and the protection of the 1998 Agreement" which I assume means most areas of the acquis. And it follows that if they apply in NI they must also apply across the whole of the UK. Effectively, the EU and the Irish have a veto. There is no other way to read it is there?
One can't help but think the UK government should have thought earlier, deeper and longer about the Irish border problem. As it is the issue has not been resolved only pushed down the road a bit further awaiting an "agreed solution". No doubt more reaction will come in as the day goes on.
