If you are upgrading from a version earlier than 1.3 please read the following:
Excerpt lengths are now based on character count instead of word count, so you will need to increase your excerpt length values.
All your custom sidebars (those that you created only) will be removed in this update. All widgets inside these custom sidebars will be stored in the Inactive Sidebar section under Appearance -> Widgets. You can simply create your sidebars again and drag and drop your widgets from this section into your new custom sidebars.
You will also need to assign your custom sidebars to your posts/pages again. You can mass change the sidebars by opening _dbUpgrade.php in a text editor located in the help folder. Add your custom sidebar ID where indicated. Now upload the file to your WordPress root directory (where WordPress is installed) then call it once from your browser like so: www.your-site.com/_dbUpgrade.php.
If you are upgrading from a version earlier than 1.2.1 please read the following:
Posts/Related Posts shortcodes: orderby="random" changed to orderby="rand".
If you are upgrading from a version earlier than 1.2 please read the following:
If you have changed the Layout, Frame and/or Padding options on individual posts/pages you will need to reapply these settings. Note: You can globally change these settings from Appearance -> Theme Options page if they are set to "Default" on individual posts/pages/reviews.
Changelog from version 2.0 to 2.1 (17-Mar-14)
Tweak: Adjusted list styling to reduce conflicts with plugin list styling
Fix: Prevented logo from not showing in Internet Explorer 9/10
Fix: Stripped any tags from link titles and image alt text
Fix: Added class and function checks to Bounce Plugin to prevent conflicts