This could be the greatest shake-up in the 65-year history of the NHS

The greatest impact may come from the decision to publish data on safety

The terrible beauty that is Andrew Lansley's huge and controversial reshaping of the National Health Service in England lurches into life today. Some 160 NHS organisations are being abolished and well over 400 new ones are being created – including NHS England, the biggest quango of them all and until now known as the NHS Commissioning Board.

Patients, of course, will notice no immediate difference. Not tomorrow, not next month. Doctors will still go on doctoring, nurses nursing. Your local GP surgery and local hospital is not going to be revolutionised overnight.

But the decision to hand over the commissioning of the bulk of NHS care to GP-led organisations – the clinical commissioning groups – with the more specialised care commissioned by NHS England, with local government taking responsibility for public health, and with EU procurement law more clearly enshrined in the NHS than in the past may, over time, prove to be the most significant change in the way the NHS works in its 65-year history.

It is already well-known that legislating for this new approach was one of the biggest political and policy making train crashes on record. It immolated David Cameron's drive to "detoxify" the NHS as an issue for the Conservatives. It hugely damaged – and tore apart – his Liberal Democrat coalition partners. And its sheer complexity is best summed up by the observation of Simon Burns, the then health minister, that "you cannot encapsulate in one or two sentences the main thrust of this".

Which makes prediction of its likely impact extremely difficult. Critics see it as "hollowing out" the NHS and fragmenting it as private sector providers take a bigger share of NHS business. Proponents believe a dose more competition will improve quality and costs. Meanwhile at least some neutral observers are impressed by the vision of the future being displayed by the leaders of some of the more creative clinical commissioning groups. They are devising plans to shift more care out of hospital and closer to people's homes while making the service more responsive to patients.

What is clear is that not since the Conservatives' introduction of the original "internal market" into the NHS in 1991 has there been so much uncertainty as a reform takes effect. Controversy still rages around the new rules for putting NHS services out to tender.

In an attempt to make this immensely complicated new universe work, a set of changes that was intended to cut bureaucracy has spawned so many new bodies that there simply isn't room to list them all. A review aimed at cutting this bureaucratic burden is already under way.

The great irony of all this, of course, is that Andrew Lansley could have achieved the bulk of what he wanted with little or no legislation. Had he done so, the NHS would be much further down the road to putting the best bits of this into practice, rather than having wasted three years and several billion pounds in redundancy and other costs.

The other grand irony is that the biggest impact for patients may come not from all this structural upheaval but from the decision – if it is implemented – finally to publish far more data on the safety and quality of services and of patients' experience of them.

That has the potential to drive significant improvements in services and changes to them, even as the money going into the NHS – which is the real $64,000 question – gets ever tighter. And doing that, of course, required not a line of legislation.

Nicholas Timmins is senior fellow at the Institute for Government and the King's Fund