Apple still strong at 40, but are best years behind it?

Apple boasts that more than 1 billion devices iPods, iPhones, iPads, Macs and Apple Watches are in regular use around the world

Apple turned 40 on Friday, and it's a very different company from the audacious startup that Steve Jobs and Steve Wozniak launched in a Silicon Valley garage in 1976.

Today, the maker of iPhones and Mac computers is the world's most valuable public corporation, with 100,000 employees and a new, multi-billion dollar headquarters in Cupertino, California, set to open next year. But despite its astounding financials Apple reported $53 billion in profit on $233 billion in sales last year some critics have suggested Apple's best years are behind it, as it has struggled to come up with new products and match the phenomenal success it has had in recent years.

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Not surprisingly, longtime employees like software vice president Guy "Bud" Tribble disagree. "We still think we're going to change the world," said Tribble, one of a half-dozen Apple staffers selected by the company to briefly reminisce with reporters this week. Tribble started with Apple in 1980 and worked on the original Macintosh team.

He added: "We had no idea back then that Apple would grow to the size that it is."

The company now boasts that more than 1 billion Apple devices iPods, iPhones, iPads, Macs and Apple Watches are in regular use around the world. Those products are widely admired and imitated. But Apple depends on the iPhone for two-thirds of its revenue. And after selling a record number of iPhones last year, analysts say sales are leveling off and may even decline this year.

As it enters middle age, Apple may find it difficult to maintain its leadership in the industry. Some experts say it's getting harder to come up with new advances to distinguish Apple's products from those of its competitors.

"Apple is still as good as it used to be, but everyone else has gotten better than they used to be," said James McQuivey, a tech analyst with Forrester Research.

He cited longtime rival Microsoft, once viewed as an industry laggard, but now credited with pioneering tablet computers with detachable keyboards a category even Apple is embracing with the business-oriented iPad Pro.

By contrast, he noted, Apple's latest iPhone is a downsized version of earlier models.

Longtime staffers said Apple still has the zeal to create revolutionary products.

"We've done this more times than anybody else," said Greg Joswiak, a 30-year employee and vice president for product marketing. He listed the iPod, iPhone, iPad, iTunes and the company's online App Store, the new Apple Watch and recent initiatives to create new health-tracking and medical-research apps for the iPhone and Watch.