"You talk to a lost different people who live in Chicago, they're always going to call it the Sear Tower. That's the general consensus on the street," said Tanisha Robeson
"I don't like it. All of a sudden it's not sears tower anymore. It's kinds of odd," said Ben Gines.
The CEO of London-based Willis Group Holdings- the tower's new namesake- doesn't understand why the Windy City is having so much trouble with the renaming.
"I don't get this. Sears hasn't been here since 1993. A lot of people are moving out. I'm moving in. I'm spending money. We're trying to do something to revitalize the place. I don't understand," said Joseph Plumeri, Willis Group Holdings CEO.
The Willis Group will occupy 140,000 square feet of office space and plans to paint the tower green. Earlier this month, the group opened glass-bottomed balconies on the sky deck (Photos; they also plan to add a 50-story luxury hotel for tourists.
Mayor Daley backed the plan and was there for the ceremony on Thursday. RAW VIDEO: Mayor Daley on hand for name change
"And you saw out there the enthusiasm of the employees. You don't see that much in any company. But they're enthusiastic. They have jobs. Their families are situated here. They move people in," said Mayor Daley.
Analysts say the reluctance of many Chicagoans to let go of the name Sears Tower is expected, but it will happen -- eventually.
"It takes a little time. Often it's a generational change. So if they're here for the long haul, maybe people younger than myself will be calling it Willis Tower," said Ty Tabing, Chicago Loop Alliance. SLIDESHOW: Other major Chicago name changes
Willis Group Holdings has donated $100,000 to the Chicago 2016 bid; the company plans to be involved in the community, according to the CEO.