Google has announced version 12.0 of the new AdWords Editor. It comes with a design refresh and a bunch of new features. 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.”

Forum discussion at Google+.