Basically they collate all your documents together, but you still have to do all the background work that you would have to do if you were handling your own application.
There have been a lot of complaints about immigration consultants in the past but it looks like something is being done about it now.
NZ immigration advisers regulated
5:00AM Tuesday July 08, 2008
The Immigration Advisers Authority issued its first licence yesterday, marking the beginning of industry regulation and protection for the rights of migrants, a spokesman said.
By May 4, 2009, immigration advisers will need a licence in an initiative to stop "rogue operators destroying the financial and personal hopes of potential immigrants to New Zealand", authority registrar Barry Smedts said.
From
here.