The new features include the ability to manage campaigns at scale, including custom rules, faster account downloads, and a design refresh. Here are the specific changes according to the release notes: - Custom rules: This version lets you create and edit custom rules that notify you of violations to best practices before posting changes. - Faster version downloads: AdWords Editor now migrates more of your data from the previous version when you download a new one. This makes downloading a new version of AdWords Editor faster. - New design: Version 12 features a new design with easier navigation. - Maximum conversions bidding: This version provides full support for the Maximum conversions bid strategy. - More videos and images for universal app campaigns: You can now include up to 20 videos and 20 images in universal app campaigns. - New optional fields for responsive ads: Several optional fields have been added for responsive ads, including “4:1 logo,” “Price prefix,” “Promotion text,” and “Call to action text.” Get the full story at Google Inside AdWords Read also "AdWords Editor’s new custom rules let you quickly see what’s missing in your accounts" at Search Engine Land