Logistics Studio has been using 3.0 for since development started with no issues, and today have upgraded several sites to the platform flawlessly.
We converted our old theme to a customized version of the Twenty Ten Default theme about a month ago. Since then a deep appreciation of the new release has developed inspiring us to use this theme as our development base much like Kubric had been used for years.
As always before updating make sure that your database, wp-config, and all of wp-content are backed up just in case.