There are so many shortcomings and problems with the new 2023 GUI interface. Here are just a few:

1. Swapping left and right-hand panels for no reason. This does not improve anything for users. It just forces users to change everything about how they work in Acrobat every workday.

2. Functions are indicated by random icons. In the 90s, we learned that icons in software and websites don't work across different populations. Users have a difficult time figuring out what the heck they mean. Give text labels.

3. The left panel is permanently positioned on the screen and obscures part of the document below. Seriously Adobe, WTF.

4. The entire menu/panel system can't be customized, moved, or docked. Another WTF.

5. Hamburger menus (those obscure 3 horizontal lines) are used on mobile interfaces to collapse menus. They are totally unnecessary and inappropriate on desktop interfaces — where working people spend most of their time working. Give people real menus with real names. "Menu" is not accurate, either. What is the name of the other menu to the right? Menu 2? Cheeseburger Menu?

6. The new interface is inaccessible for those with disabilities who use assistive technologies, especially screen reader users. Adobe has seriously violated its VPAT with governments and corporations worldwide who are required by law to provide accessible work environments and tools.

7. Grey on Grey is not an accessible color scheme. Can't tell if some icons are active or disabled. Those with low vision can't discern the icons.

8. Digital signatures, Document Cloud (where Adobe stores your files by default), subscriptions, OCR, file creation, file combining, and accessibility all have reported major problems for the past few years...but rather than fix these critical problems, money was instead spent on rearranging the deck chairs on the sinking Titanic.

As long-time PDF consultants, my firm has found that the majority of customers are professionals who use Acrobat for their jobs. These are not "casual" users working on their smartphones. They are using desktops/laptops with full screens, not mobile devices to do their jobs. And they work with PDFs a lot.

They have developed actions and scripts to automate processes on dozens, hundreds, and even thousands of PDF files every day. These industries include print, prepress, graphic design, accessibility & remediation, accessible forms, variable forms, variable printing, data validation, financial institutions (think of all those bank statements every month!), health care, investment and finance, and manufacturing.

Dramatic GUI changes like 2023's completely change how these automated processes work...if they still work at all.

The cost to these industries to correct the now-broken processes — brought on by Adobe's whimsical, untested design idea — is appalling. If I was a major corporation hit by this unnecessary expense, I'd ban Adobe products from my company and look for another PDF vendor.

There are now many reputable competitors to Adobe Acrobat: See:
— https://www.tomsguide.com/best-picks/best-pdf-editors
— https://www.techradar.com/best/pdf-editors
— https://www.pcworld.com/article/407214/best-pdf-editors.html

Calling this Acrobat's "Modern Viewer" is a form of gaslighting Adobe customers. It's not modern at all — 30 years ago, using icons failed in software and web interfaces, and it's failing again with Acrobat 2023. Sometimes retro isn't good, especially retro user interfaces. Please don't attempt to bring back disco, old-fashioned 20 inch TVs, polyester suits, rotary phones and VHS tapes as being "Modern," too.

Ditch this "Modern Viewer" and instead give us a working tool to get our jobs done.

1. Revert the interface back to what it was.

2. Fix Acrobat's bugs. There are so many!

3. And improve the accessibility for those with disabilities (who can't get to the Comments panel, Bookmarks panel, understand what and how much is redacted, make edits or change the content, scale/enlarge the interface, nor sign a PDF).

For those still reading this, users can revert to the old interface for now (August 2023).
— Windows: Hamburger Menu / Disable New Acrobat
— Mac: View Menu / Disable New Acrobat

I have no idea who long Adobe is going to let us revert to the "real" interface.