WU (Windows Update) will consolidate all the restarts in a month, synchronizing with the monthly security release. This means that your PC will only restart when security updates are installed and require a restart. With this improvement, it does not matter when updates that require restarts are released in a month, since these restarts will wait till the security release. This simplification helps in three ways: it keeps the system secure in a timely manner, reduces restarts, and makes restarts more predictable. Only exception to this being in the case of critical security update to fix a worm-like vulnerability (for example, a Blaster worm). In that case, WU will not wait, but will go ahead and download, install, and restart automatically. But this will happen only when the security threat is dire enough.
WU notifies you of any upcoming automatic restart. Suppose, WU has already detected, downloaded, and installed security updates, and now requires a restart. Windows Update will notify you of an upcoming automatic restart through a message on the login screen that will persist for 3 days.