If you choose to localize your application you have the option to customize the localization settings, which may have an impact on your deployment procedure.
Adding themes to your application requires that you deploy the style and image files to the appropriate place on the server. The Styling and Theming in Ignite UI topic includes details on how the files should be organized.
Sometimes your application is required to run in some old contexts. Make sure to read Using Ignite UI in Browsers Without HTML5 or CSS3 Support to mitigate any issues working with old browsers.
If your deployment includes an upgrade in Ignite UI, then the Upgrading Projects to the Latest Ignite UI Version topic includes the details to help you make a smooth transition.