The good news is that, formally, Brexit is done. The transition is over and relations between the UK and the EU are now on a continuing and agreed basis.
Reaching agreement with the European Union was a major achievement for both Boris Johnson, on behalf of the UK Government, and the EU's Ursula von der Leyen.
In terms of diplomatic achievements, they both deserve congratulations because they have agreed a deal that (with marginal exceptions) meets the ambitions they gave to their negotiators.
The drafting of the huge agreement is, as ever, a clever use of language and an elegant avoidance of clear differences on major principles.
Boris Johnson has gained the freedom that the UK can now make its own laws.
Ursula von der Leyen has held the UK in an acceptably close, but independent, relationship and at the same time has demonstrated to any other country tempted to leave the EU that withdrawal can be a painful process.
Time will show whether the decision-making embodied in the new agreement has kept a close interdependence between both parties sometimes disguised behind co-operative arrangements.
On the island of Ireland, or between both of the political entities on this island, we now have one of the more complex political and economic settlements in western Europe, designed to minimise the disadvantages of a fractured economy and retain highly integrated social living between two political systems.
The challenge now is, while respecting the political differences, to develop a strong island economy drawing on the strengths of this setting alongside the UK and the EU.
The seamless integration that served this island well during 40-plus years of EU membership has now given way to a form of economic and social organisation that can still function well if the stitching of the newly-created seams is good enough to strengthen the end result.
To cope with the consequences of leaving the EU, for the mutual benefit of both jurisdictions, we have a diverse multi-layered network.
Early in the Brexit negotiations, there was an understanding between the British and Irish Governments that, replacing the freedom of movement created by the EU, the governments would reactivate the freedoms of the Common Travel Area that for many years has allowed British and Irish residents to live anywhere in these islands.
To date there has been no suggestion that a formal residency qualification would be introduced, although such a step would be consistent with the post-Brexit regime in Great Britain. The new agreement also paves the way to continue arrangements for reciprocal rights to emergency medical treatment and for the cross-national payment of certain social security benefits.
By parallel coincidence, the UK and Irish Governments have inherited a series of policies and institutional arrangements for cross-border co-operation in Ireland.
The Inter-Governmental Council, along with specific institutional arrangements for road and infrastructure projects and for tourism and inland waterways, gives scope for continuing jointly agreed policies.
The new agreement between the EU and UK also contains two specific references that will ensure continued cross-border public passenger services and for the continued functioning of the Integrated Single Electricity Market.
Since the island of Ireland will continue to host two different political policy areas, there will be a degree of competition, north and south, to stimulate business development and grow the economies.
That competitive outcome could be a source of strength or, if not carefully managed, might miss out on opportunities for complementary gains or more beneficially might (if used with too great a degree of protection) be used unintentionally to mutual disadvantage.
An important factor in the operation of the new political structures will be the interpretation of the UK-EU as it relates to the (so called) level playing-field in making economic policy.
At first reading, the UK Government has not accepted the constraints as commended by the EU Commission.
Closer reading of the text as now published is not so clear-cut. There will be a close interest in the evolution of a new regime on State Aid.
The accord has excluded a formal agreement but the wording of the guidance for policy-making leaves scope for the avoidance of competitive policies giving ' a race to the bottom' to attract development.
Northern Ireland has now inherited a network of opportunities for co-operation in securing development.
The challenge, for businesses and the Executive, is to maximise the benefits from the changes.