1. No way to turn off What's New shelf, nor even a way to move it to the bottom.
1'. What's New shelf still takes up a huge amount of height in the library display area at lower window sizes for the Steam client. This is noticeably more than 50% of the library display area height when the library is at its smallest allowed resolution (1010x600), and this also causes the next shelf below it to have its portraits cut off.
1''. What's New still not available in a much less intrusive button-to-dedicated-page form the way it's done in Big Picture Mode.

2. No way to use List View or something comparably densely-packed with information about the games in our library.
2'. No way to sort by one attribute while seeing other attributes that would have been visible in List View.
2''. No way to reverse-sort by attribute, as was possible in List View.

3. No way to turn off images in library. No plaintext display of game names in main library view.
3'. Forced vertical cover displays; no horizontal cover display version.

4. Still lags by about 7 seconds when scrolling, just to load images. Due to lack of plaintext display of game names, this means that the main library is unusable while waiting for the scrolling to resolve.

5. Main library view is still not keyboard-navigable.
5'. Left sidebar is navigable via arrow keys but the games are still not keyboard-launchable. (I suppose this aspect is a little less important since the sidebar by itself is not very useful, and Small Mode provides a keyboard-launchable list.)

6. Mouse-over still produces a slideshow of store page screenshots, only pausing the slideshow, not actually removing it entirely.

7. Small Mode still unable to uninstall games, due to requiring browser-rendered confirmation prompt page.

8. The status icon showing whether the game is installed or not is inexplicably pale and hard to see. (This probably works better if you have a lot of dark-colored game cover art, but that's way too specific for something that ought to be universal in usage.)

Do please correct me if I am wrong on any of these details. (Note that I have not addressed game detail pages because I don't even use them.)

If the above information is accurate, I would continue to suggest that users experiencing similar issues do any or any combination of the following:
* unofficial methods for manual removal of the What's New section (multiple methods available).
* launch Steam with the parameter -no-browser (which causes the entire primary llibrary UI to become blank) and just use Small Mode. Use Big Picture Mode to uninstall games. (WARNING: do not attempt an uninstall from Small Mode then go to Big Picture Mode to uninstall it; that will basically cause the uninstallation process to hang on an unresolved confirmation prompt that can't be displayed. Go straight to BPM to uninstall; it will then use its own prompt.) Added benefit of doing this is that it reverts to the old Friends List version, if you are interested in reverting that.
* use the various resources floating on the internet to revert the Steam client version to an older version and prevent it from updating past that version. (WARNING: this may result in lack of access to some games.)
* use other means to launch games, which may include but are not limited to other launchers, as desired (I personally don't care for one though).

I, personally, have been using -no-browser with Small Mode, and handling uninstalls through Big Picture Mode. Furthermore, I have been avoiding any further purchases on the Steam platform, and I will continue to avoid purchases on the Steam platform until these issues are addressed. I encourage other users experiencing similar issues to do likewise.

Edit: adding point 8.