Part 15a of my ConfigMgr 2012 SP1 Step by Step Guide describes the notification behaviour and user experience of software update deployments. Please read in conjunction with Part 15 of this guide - Software Updates (Microsoft).
The following screenshots show the behaviour using ConfigMgr 2012 default settings.
Open Client Settings > Computer Agent
Deployment deadline greater than 24 hours – remind user every 48 hours
Deployment deadline less than 24 hours – remind user every 4 hours
Deployment deadline less than 1 hour – remind user every 15 minutes
See restart options
Display temporary notification to the user that indicates the interval before the user is logged off or before the computer restarts – 90 mins
Display a dialog box that the user cannot close which displays the countdown interval before the user is logged off or before the computer restarts – 15 mins
I like to choose the option above when deploying the updates - show all notifications to the user and show in software center.
I also like to configure update deployments with a deadline of 1 week away (this is the default setting).
When the device retrieves policy the user is notified that updates are available.
User receives notification. The user is invited to "Click here for options".
If the user "clicks for options" they are informed that updates are available with a deadline of 1 week. They are invited to "Apply all required changes now" or can click to "Remind me later". Most users will choose "Remind me later".
The software update information is available in the Software Center.
When the deadline arrives the updates are downloaded to the computer cache. Note that this does not happen exactly at the deadline time.
It is not a great idea to deploy updates to thousands of machines at exactly the same time. Therefore each client adds a random time of up to two hours to the installation specific deadline time. This random additional time isn't configurable. (Note that Deadline Randomization is now disabled by default in SP1).
Now the restart countdown commences (90 minutes by default).
The user is notified.
The required restart can be seen in the Software Center
Click the balloon notification to see the dialog box. The user can Hide the notification at this time. Note that even when the balloon notification disappears the restart timer remains in the system tray. The user can click on the restart timer icon in the system tray at any time to open the dialog box (assuming of course you haven't hidden notifications in the system tray).
User receives additional notification of pending restart, which can be hidden.
Countdown has entered last 15 minutes. The user is notified by a dialog box and the notification cannot be hidden or minimised. It will remain in the foreground until the computer restarts. All other applications remain in the background - no excuses for the user.