“The other way was better,” Amilcar Zani said as he stood in the Great Hall of the Metropolitan Museum of Art during his visit from Brazil. Mr. Zani, a pianist and music professor, had just learned that he was now required — as a nonresident of New York State — to pay $25 under the museum’s new admission policy, which went into effect on Thursday.

“This is a museum for the City of New York,” he added. “It’s a surprise.”

The museum has gone to great lengths to prepare for Day 1 of its momentous change, from a 50-year policy of “pay what you wish,” announced in January. But the Met also knew that some glitches and growing pains would be inevitable.

“We worked very hard for it not to be bumpy,” said Daniel Weiss, the Met’s president and chief executive officer. “We’ll get better at it. We’re going to do everything we can to welcome people and move them through.”

[The scene at the Met on the first day of the new fee policy.}

Some out-of-state visitors on Thursday were taken aback by the new mandatory admission. “Horrible,” said David Walker, 34, who had come from San Francisco to take his friend Marquis Engle to the museum on the occasion of his 27th birthday. “I feel caught off guard.”