"I'd give them an A for the apology, but a B+ on the timing and the audience," said Andy Stoltzfus, a digital strategist with Levick Strategic Communications, a Washington, D.C. firm that helps companies deal with public relations emergencies.

"They should have gotten their act together earlier," Stoltzfus said.

Stoltzfus graded the performance of Joe Belfiore, Microsoft's top executive for Windows Phone, who on Wednesday gave the yet why promised updates for Windows Phone 7 haven't reached customers.

Microsoft has struggled to explain the delays for more than a month.

Several weeks ago, Belfiore said that most users had gotten a February update, a claim he admitted on Wednesday "was wrong." Before that, Microsoft CEO Steve Ballmer had said that a larger update, nicknamed "NoDo," would be released in the first half of March. Shortly afterward, however, a Windows Phone 7 manager retracted Ballmer's pledge, saying NoDo would arrive later.