Keeping your self-hosted WordPress blogs up to very important to prevent technical issues and to close security holes that have been discovered. WordPress.com users don’t need to concern themselves with these upgrades as WordPress.com handles that internally for all its users.
I just completed the upgrade on 4 of my WordPress sites with no problems. I use the automatic upgrade feature built into WordPress which basically consists of pushing a button.
Log into you WordPress sites today and keep them upgraded for trouble free operation.