Nokia CEO Stephen Elop is under pressure to justify a decision to ditch the company’s smart-phone software in favor of Microsoft’s, his former employer.

Nokia Corp., the world’s largest maker of phones, announced the alliance with Microsoft Corp. Friday. In a show of displeasure, Finnish employees used flex time to go home early.

“Every employee goes through an emotional journey, and the emotional journey is difficult, because this is such a big change,” Elop said Monday, in an interview. “There’s a lot of work ahead, a lot of work still to be done.”

Elop, a former Microsoft executive, was hired in September to shake up Finland-based Nokia, which is losing market share quickly in smart phones.