This week, he traveled to Paris to the Le Web conference do an onstage interview with Gigaom's Om Malik.
We've found the video of the interview and posted it below. If you've never seen Nadella in action, this interview shows him off to good effect.
Unlike Ballmer's straight-from-the-hip style, Nadella treads carefully with his words. For instance, he comes close, but never actually admits that Microsoft has stumbled in key areas, like mobile computing:
"You renew yourself every day. Sometimes you're successful, sometimes your not, but it's the average that counts," he said in the interview.
He currently heads up Microsoft's cloud computing efforts. Under him, the unit's revenue grew to $20.3 billion in the fiscal year that ended in June, up from $16.6 billion when he took over in 2011, reports Bloomberg's Dina Bass and Marie Mawad.
He's also known internally as someone that's good at getting warring factions to work together, Bloomberg reports.
That's an important trait for the new CEO since shortly before announcing his resignation, Ballmer reorganized Microsoft to try to get business units to cooperate better. He even named the reorg "One Microsoft" (and crafted it with the help of Ford CEO Alan Mulally, known for doing the same at Ford).
Ballmer is helping to choose the next CEO, so it's likely he'll want someone who will keep treading along this same path, a former Microsoft headhunter told Business Insider.
Most recently, Nadella has helped Microsoft's cloud, called Azure, gain respect as an alternative to Amazon's cloud among the industry.
"Three years ago, you would have written off any Microsoft cloud push as ill-fated, but Azure is now a real contender," Aaron Levie, CEO of online storage startup Box, told Bloomberg in an interview.
So here's a closer look at a man who could soon be running Microsoft: