Windows 10 has been released officially about two years ago and in addition to a new interface, new functionality and integration with mobile platform, it will automatically install updates that typically, you avoid or defer them.
Windows is an operating system from service, a foundation for other programs and the cloud. With this step, Microsoft wants to ensure that all systems are “up to date” in terms of safety and requires all updates to be installed automatically, and this without informing yourself.
This detail is mentioned briefly in the EULA (No: you conclude an agreement with Microsoft, you install Windows 10) attached to the newest preview of Windows 10 (Build 10240). With Windows 10 (Home version), Microsoft does not want to leave them so much control users, and this can displease especially those using pirated versions.
In recent versions of Windows, you could choose to download and install or not to check, do not download and install not never no update. The good part is that the operating system will be more secure, Microsoft identifies security or stability problems and solving them. But there is a downside.
As no software is perfect, updates may have problems. There have been instances in the past, although less than where vulnerabilities were exploited by hackers because people had not updates. However, as noted by The Verge, Microsoft has 5 million people who tested Windows 10 and may be based on those to see what works and what does not.