Usually you upgrade the BIOS if there are bug fixes or feature improvements that affect you... otherwise, if it isn't broken, don't fix it!
Check the change log for the BIOS to determine if you need to upgrade.
I've upgraded the BIOS for my desktop and it was hassle free... but... could easily have resulted in disaster, too... so... use caution when upgrading the BIOS.
And this should go without saying, but... if you do upgrade the BIOS, make sure you are plugged in and have a fully charged battery first... last thing you want is the BIOS upgrade to fail due to power outage.