So, how should Microsoft shareholders judge Nadella's performance after 12 months on the job?
For one, look at the company's financial results. Under his watch, its revenue has jumped 12 percent to $93.5 billion.
While positive, that's a mixed record compared to other high-profile tech executives.
It's not nearly as strong as Apple CEO Tim Cook , where revenue surged nearly 50 percent in his first year on the job to $148 billion.
But it's better than IBM's Ginni Rometty, where the top line slumped 2 percent to $105 billion during her first year running Big Blue.
Another important metric: Stock performance.
Since Nadella took the helm, Microsoft shares are up about 15 percent, basically in-line with the S&P 500 and the Nasdaq over that same time frame.
But, beyond financial metrics, there's also the broader question of whether Nadella is pursuing a smart business strategy for the company he runs. Analysts say he is.
"Finally, what we have is a CEO that is willing to skate to where the puck is going in terms of cloud and mobile and making tough cuts," said Daniel Ives, managing director at FBR Capital Markets. "There is much more openness to take Microsoft into this next paradigm shift that we're seeing on the cloud."
In its last earnings report, Microsoft disclosed that its commercial cloud business boasted triple-digit revenue growth for the sixth straight quarter.
Some analysts also cheered Nadella for another reason: they say he's a better fit for the company at this time than his predecessor, Steve Ballmer .
"Nadella is a developer while Ballmer was really a sales guy," says Patrick Moorhead, president of Moor Insights & Strategy. "There are great things to sales guys but, when people are looking for growth, they want to hear from the developer in the company."
"What Microsoft was lacking a bit was the connection to those developers and to those involved in technology. Nadella just brings that confidence to the table," Moorhead said.
However, some analysts argue that the first-year honeymoon ended for Nadella when Microsoft last reported earnings results on Jan. 26. The stock dropped hard after that report.
Part of the worry? Underlying trends for its Windows franchise.
Last year, Microsoft ended technical support for the Windows XP operating system, motivating companies to upgrade their computers. That tail wind might not prove as strong this year.
Looking ahead, with the company's stock now down 17 percent from its recent high, analysts say that one of Nadella's primary challenges is demonstrating strong momentum in its mobile business.
The most recent evidence from research firm IDC shows Microsoft controls less than 3 percent share of the smartphone market dominated by Google's Android and Apple's iOS.
Also, Windows 10-the new version of its operating system due out later this year-needs to be a big hit.
Windows still accounts for about 25 percent of Microsoft's revenue. Companies, consumers and developers need to embrace Windows 10 if Nadella hopes to win over Wall Street in 2015 and beyond.