I upgraded this site along with lots of others tonight as I watch the NBA Finals. GO HEAT!
A word of warning, if you are using the DB Cache Reloaded Fix plugin. Upgrade the plugin first before upgrading to WP 3.4.
Of course, you may also want to follow the official directions regarding upgrading WP by disabling ALL plugins first. I usually don’t do that but I do recommend backup up your site files and db before upgrading. Best choice for doing that is BackupBuddy!