Several opening events attracted big crowd and more events are planned over the next week.
Tours, which gave hundreds of people the chance to see the interior for the first time, were a big success and most gave the Waitaki District Council project the thumbs up.
Not only the standard of the restoration, but also the creation of so many different rooms to make the Opera House more versatile, won praise.
Tom Weir, of Oamaru, described the restoration as "excellent", particularly its multipurpose use.
He is involved with a "Friday night club" which caters for 7- to 11-year-olds and said the Opera House would be a good venue as numbers continued to grow.
Colin Mckay, of Maheno, considered the $10.4 million had been "well spent".
As a ratepayer, he appreciated seeing something good made of the Opera House.
"I take my hat off to what they have done - it's magnificent."
An Oamaru woman, who did not want to be named, had been an usher in the Opera House when it showed movies and said the redevelopment had made a big difference to the building.
McCall and Jerome Prentiss, with their 2-year-old son Jerin, are from Hawaii and stayed two days in Oamaru to attend events at the Opera House.
They could not believe the town had such a facility.
The opening events started on Friday night with a civic reception attended by about 200 people.
It was hosted by Mayor Alex Familton, who announced new sponsorships of rooms in the Opera House by Whitestone Contracting Ltd (the auditorium), Otago Daily Times (Ink Box room), Meridian Energy Ltd (the board room) and Whitestone Cheese (the Empire room).
Mr Familton described reopening the Opera House as a "significant day, a historical milestone and of national importance in the preservation of heritage buildings".
The project was instigated in 2006 by a casual "coffee club" made up of former mayor Alan McLay, former deputy mayor and now Waitaki MP Jacqui Dean and businessman John Walker.
On Saturday evening, street entertainment had to be cancelled because of rain but a dinner in the Empire Room and a Gala Showcase went ahead.
The biggest events were the religious service yesterday morning - all 500 seats in the auditorium were full, with another 100 people standing, and the tours yesterday afternoon.
About 100 people turned up for the free Inky kids event in the Ink Box and the Great Debate last night also attracted a good attendance.
