For nine long years Labour MPs have complained, loudly and bitterly, about the failings of the National-led government.

The housing crisis, the desperately under-funded health system, the appalling flaws in prison management, the chronic inability to do anything about Auckland's gridlock, the awful plight of mental health patients, grave lapses in biosecurity... those were just some of the front-runners.

There was also the more generalised condemnation - people "missing out" on the nation's prosperity, the dreadful lives of the working poor, child poverty levels that were a disgrace to a developed country.

"This is not the way we want New Zealand to be," the MPs said, again and again.

Now they've got the chance to do something about it, and voters will expect them to deliver.

It starts at the top, and Prime Minister Jacinda Ardern hasn't shirked her share. The cabinet list shows, next to the usual prime ministerial roles: Minister for Child Poverty Reduction.

National will target her mercilessly on that one if she doesn't bring the rate down - and it's measurable.

Then there's Phil Twyford, a trenchant critic of National's housing policies or, as he saw it, the lack of them.

Twyford persistently claimed the government wasn't building houses - and now he's in charge of Labour's KiwiBuild scheme designed to deliver 100,000 in the next 10 years.

And first home buyers will be able to afford them, that's the claim.

It won't be long before he's asked in parliament: "How many KiwiBuild homes will be completed and sold in 2018, and how much will they cost?"

Twyford is Minister of Housing and Urban Development, and Minister of Transport as well.
If the opposition doesn't nail him on housing, there another big target on his back for them to aim at.

Carmel Sepuloni has taken over the huge social development portfolio, previously Anne Tolley's responsibility.

She'll have to live up to expectations that a Labour-led government will repair the "broken" welfare system, particularly the way it looks after vulnerable children.

Those stories about children being kept in police cells because there isn't enough space in secure youth facilities will come back to bite her if she doesn't do something about it.

And remember Kelvin Davis, the MP who broke the prison fight clubs story?