Satya Nadella's first year report card

A year ago Wednesday, Satya Nadella moved up from the ranks to take the helm at Microsoft. He hasn't been sitting still.

Since the beginning of his tenure, Nadella has promoted Microsoft as a mobile-first, cloud-first company,

He has given the Windows operating system an upgrade and a new reputation. Windows 10 will have the same look and feel as the previous versions but will be available on any device.

Unlike in the past, upgrading will be free for Windows 7 and 8 users. Momentum around Windows 10 has been building for its launch later this year.

Nadella also recognizes Google's Android and Apple as rivals, coming out with its own cool gadgets to compete. Last month, it announced augmented reality glasses, HoloLens and the Microsoft Band in the wearables space.

Satya Nadella, chief executive officer of Microsoft Corp.
Jin Lee | Bloomberg | Getty Images
Satya Nadella, chief executive officer of Microsoft Corp.

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Another bold move by Nadella was making its Office suite—Word, Excel and PowerPoint—available for free on Android tablets.

An app for Microsoft's Outlook email program will run on iPhone and iPads, in an effort to build mobile user growth.

In his first year Nadella has made a lot of changes, but what lies ahead might be even more important to analysts and investors. Can the the PC recovery can be sustained, how can Microsoft win on tablets and what's the future of its cloud strategy? These are just a few challenges investors will be watching.