A few of my personal pet peeves (note: every disgruntled user has their own, largely disjoint set):

1. The applet to inhibit screen sleeping went away. Without it, I often look up from working on a hard problem to discover that my screens have been blanked out.

2. Something GNOME-ish keeps grabbing my mouse, and won't let it go until I log in with SSH and start killall-ing anything with "gnome" in the process name. It happens once a day or so, I haven't been able to purposefully reproduce it, and it's really annoying.

3. The settings applet was neutered. It now looks like a cheap knockoff of MacOS's system settings, except somehow with even less functionality. It also seems like the GNOME developers simply forgot about it until about a month before the release, because many features that appear to be present are barely functional. For example, Appearance -> Theme only changes gtk3 themes, and most of the gtk2 themes don't have a gtk3 counterpart, so now about half of my apps don't look like the other half. Another example: the new settings applet stores network proxy settings somewhere weird now, so neither Firefox nor Chrome find my proxy settings any more.

4. About half of the GNOME configuration has moved to gconf to dconf, but there's no rhyme or reason as to which half. When I discovered the new settings applet, I tried to change stuff with gconf/dconf, except I have no idea how to figure out which applications use what settings storage backend.

5. A lot of applications don't have key bindings any more, or had them greatly reduced. GNOME 2 was pretty good about this, but many GNOME 3 applications are completely unusable without using the mouse.

> 1. The applet to inhibit screen sleeping went away. Without it, I often look up from working on a hard problem to discover that my screens have been blanked out.

The Presentation Mode shell extension fixes this - adds an option to the drop-down menu on the power meter to turn on presentation mode, disabling screen blanking & locking.

> 4. About half of the GNOME configuration has moved to gconf to dconf, but there's no rhyme or reason as to which half. When I discovered the new settings applet, I tried to change stuff with gconf/dconf, except I have no idea how to figure out which applications use what settings storage backend.

I think finishing this migration is a work-in-progress.

Don't have immediate solutions for the rest of your gripes. Gnome 3 seems to be a love-it-or-hate-it thing; I find it to be great (modulo a few bugs and quirks, but it isn't everyone's cup of tea.

"2. Something GNOME-ish keeps grabbing my mouse, and won't let it go until I log in with SSH and start killall-ing anything with "gnome" in the process name. It happens once a day or so, I haven't been able to purposefully reproduce it, and it's really annoying."

That is a bug, I've not seen that on Ubuntu 12.04 using Unity or GS all through the testing period.

I gathered from what jmillikin said that it is certainly a bug, but it was probably not reported during the testing period for the same reason jmillikin didn't report it: it appears to be hard to reproduce.

Is there a tool (akin to xev) that would display which process currently has control of the mouse? I would think that tracking down the process that has grabbed the mouse would be the necessary first step toward stopping it from doing so.

I am surprised Google security would let you disable the screensaver anyway.

I wasn't able to figure out how to remove the top and bottom panels (the window list thing at the bottom and the shutdown button thing on top).

I like vertical real estate (would like to merge them into one, like I could with Ubuntu 10.10). And I like no toolbars on on top (to make it easier to click on my firefox tabs (see below)).

My favorite GUI customization is to remove the "decorations" (window frame, title bar etc) of maximized windows (to get a little more vertical space). This also makes firefox's "tabs on top" feature look the same on Linux and Windows.

You can do it with Compiz+XFCE (which I did in 10.10). Compiz isn't working for me under XFCE in 12.04, so I'm using a PyGTK script I found on the Net to do this.

If you're using Gnome 3 fallback you can add / remove applets like Gnome 2. The only difference is you have to alt + right-click on a panel / applet instead of just a regular right-click.

Most of what you want is available via extensions. The Panel Settings extension lets you turn on autohide, which addressed my primary gripe. devilspie works great with gnome3 to get rid of decorations.