==== Extracted from the Microsoft Migration to Office 365 article ====

• IT as a Service: IT was able to move from being a service runner (patching machines, managing service uptime, managing storage, etc.) to being a business enabler. Our focus is now on empowering our businesses and employees to get business value and to enable rapid solution development to achieve business results.
• Rethink opportunity: Site and portal owners at Microsoft were encouraged to use migration as an opportunity to start fresh so they could build their SharePoint site(s) just the way they would like, without rushing or building something they wouldn’t use or need.
• Anywhere on any device: Employee adoption of SharePoint services and personal storage increased after moving to Office 365 when our employees could work when and how they needed to on any device. When they were no longer tied to specific machines, employees responded by broadly using OneDrive for Business (and its precursor). They moved significant content off their personal drives onto core team sites, groups, and OneDrive for Business sites. They took advantage of new features and capabilities that came with moving to the cloud, including moving to dynamic rendering that allowed them to publish content once to PCs, tablets, and phones.
• Service simplification: We simplified our environments greatly; instead of having multiple disparate SharePoint farms for utility services and for each major customized portal farm, we moved to a single Office 365 tenancy and consolidated the remaining sites on-premises as much as possible. For example, we eliminated separate MSW, divisional, and regional MySite farms, saving engineering effort and hosting costs.
• Cloud governed: To help us manage our cloud sites, we built a custom IT site management solution we called AutoSites. This allowed us to better manage site proliferation by requiring a site manager to actively decide that their site is still useful and should be preserved. It also required each site to have a site owner who is with the company, which prevents leaderless sites from floating out there, unmanaged.
• Technical agility: We stopped managing our employees’ storage needs, instead leaving that to our cloud service. When we moved to the cloud, our employees went from collectively storing eight terabytes of MySite content on-premises to more than 350 terabytes of data on OneDrive for Business in the cloud. In the past, we would have had to provision disks of new storage capacity to cover all that new use—not anymore.
• Simplified solution isolation and deployment: Since business solutions can’t step on each other in the cloud, nor negatively impact the SharePoint farms themselves, our internal customers are able to work with us to get new applications into a central internal application catalog all backed by one Office 365 tenancy—as opposed to separate, on-premises farms for each application.
• Improve security: Because SharePoint Online is more secure than on-premises versions of SharePoint, we were able to make the way our employees and contingent staff store and save data much more secure. Significant security enhancements have been rolled into SharePoint Online. Bringing that to on-premises SharePoint farms would be difficult and expensive.
• Rapid capability evolution: We were able to move our custom portals over to the cloud with the vast majority of on-premises capabilities intact. Once migrated, we worked with portal owners to use new capabilities afforded by the cloud. For example, sites were able to take advantage of Delve (the Microsoft personalized, internal searching tool) and users could easily discover content shared with them—features that didn’t exist on-premises.
• Cost reduction: Our goal was to reduce operation costs while adding new capabilities, including enabling access anywhere on any device, improving look and feel, and using simpler, consistent publishing. We largely were able to do this while also retiring dedicated SharePoint farms, which saved hosting and service engineering costs.