A demographic study has shown about 475,000 Aucklanders live within a 15-minute drive of the new 100-shop mall.
NorthWest, a third of a kilometre long, with an area of 2.7ha (four rugby fields), is off the Northwestern Motorway at Westgate Town Centre, between Maki St and Gunton Drive.
"A fantastic day," Alexander said of Thursday, estimating around the same numbers had visited on Friday. However, it was not a "fantastic day" for several Auckland councillors.
Darby took a swipe at the mall on Facebook for potentially damaging Henderson and causing urban sprawl, adding that "the blight of Lincoln Rd was the warm-up act".
Fellow councillor Linda Cooper called Darby a killjoy.
"Thousands of people here today," Cooper said on Thursday.
"This town will be the anchor for northwest growth - the fastest and biggest growth in New Zealand. Would you rather all these local people drive 15km to Albany or 20km to St Luke's? From Kumeu, it's even further.
"Think of all those emissions and fossil fuels burnt on cars to get there. Local residents ecstatic with their jobs close to home."
Darby said the only killing of joy had been in Henderson, referring to that town centre being hollowed out by the new Westgate Town Centre.
Architectural academic Dushko Bogunovich then took a swipe at the mayor and deputy mayor.
"So much for Len Brown's and Penny Hulse's championship of the 'compact city' vision," Bogunovich wrote.
Hulse hit back, defending the development. "There is a much bigger picture here that all of you who have rushed in to criticise have missed," she said.
"The master plan for Westgate has housing, employment and commercial developments as part of this.
"The library/community centre is under way. Park land and recreation areas are set aside and if Auckland Transport ever get their act together ... the bus transport interchange designed by Waitakere will be built.
"The mall has an open street frontage and the main street builds on good urban design.
"This is a very large, complex, long-term town build ... Do not be so quick to condemn.
"People in the nor-west need jobs and with the new busway now on track, why condemn us out west to always head down the motorway to work?"