On Macintouch Don Hurter says
I cannot stress enough performing system updates one step at a time (others here have detailed their cautious procedures, so I won’t repeat them), but one additional step is to monitor the first reboot after the update using ‘verbose mode’. You can do this by holding down command-v at startup, or make it a permanent routine by typing the following into a terminal window:
sudo nvram boot-args=”-v”
Doing so will allow you to see exactly where in the boot process the system is taking its time (such as during an Airport firmware update, for example), whereas relying on the default graphical boot status leaves you guessing as to what’s happening during the long pauses.
Since users now reboot so infrequently, who cares if the startup screen seems pretty or not? Err on the side of more information, and switch to verbose mode.