Searching this forum even a tiny bit and searching online reveals a plethora of people who are very upset about this change and now you have forced it upon all users dramatically reducing productivity. Ensuring that your users feel stupid because they can't find simple things they used to do with a single click. If a user has to Google or submit a question for finding simple things they used to be able to find easily (like uploading a spreadsheet of issues is one that's in this forum, how about switching boards or seeing your own boards?)
You have destroyed any trust power users have with Atlassian by forcing these horrible changes on the community at large. Offer this "new and improved" experience as a CHOICE as a theme people can choose -- it's as simple as changing a CSS file if you do it right. Don't force it on people. Let people use the legacy system that works well and is intuitive and provides 1-click access to the most used features.
This change is absolutely absurd considering the amount of negative feedback you've received about the changes.