There is a significant amount of people unhappy with the direction of GNOME 3 who do not enjoy KDE and find LXDE too weak in features or who just like the look and feel of the old GNOME 2 desktop. Here are their options in Fedora 18, as they can be seen in the recently released Beta.
Xfce is by now an old desktop environment, with years of development and an existing community. When GNOME changed drastically, it was seen by many as the de facto replacement (before, it was seen by one as "GNOME Lite"), an important number of users adopted it, even Linus Torvalds used Xfce for a while.
Currently it is also the easiest to install on a Fedora system, there is a dedicated spin you can run as a live image on install on your computer. The spin is available also for the F18 Beta
The desktop is kind of basic, even now it looks better it still lack polishing and features and the included apps are limited in functionality. The development rate is not as fast as you may want, technically it feels a few years behind. Of course, being a GTK+ 2 desktop, you can run any GTK+ 2 (GNOME 2) applications seamlessly (note: major GTK+ apps like GIMP or Inkscape are still GTK+ 2 based).
The ideal target for Xfce are users with a limited need to fiddle with the desktop, who spend most of their time either in the terminal or a few apps and need a shell to launch those: either newbies or techies.
Cinnamon is an alternative GNOME 3 shell developed by Linux Mint which was available for some time for Fedora in a 3-rd party repo and now is part of the main repo. It forks some components from GNOME, like the window manager (Mutter - > Muffin)
Still young, Cinnamon does not have yet a dedicated Fedora spin of its own, so you can install it with yum (yum groupinstall cinnamon-desktop) on an existing installation. I did it over the Xfce spin, but it may be a good idea to install from a Desktop (GNOME) spin, as it would re-use most of the GNOME stack and apps, or even from the net-install image, if you want to keep the footprint low (none of the desktop presented here are available on the install DVD but they can be yummed later).
The desktop feels like a mix of elements from GNOME 3, GNOME 2, Windows, KDE and others, is like GNOME 3 a "modern" desktop but with a different vision. There are a lot of inconsistencies in its look: some apps have dark windows, some have light windows, some icons are flat, some not, you can easily see the team is small. On the apps side, everything is there: since Cinnamon is an alternative GNOME 3 shell, it uses all the GNOME apps.
Honestly, I am not sure what is the intended audience for Cinnamon with its mixed feeling, I guess those who want a change, but not that much in the GNOME's intended way.
Just as Cinnamon, MATE does not have a dedicated spin yet (look forward for one in Fedora 19), so you can get it with yum groupinstall mate-desktop from an existing install.
The desktop has an identical look and feel with a GNOME 2 desktop, since it is a direct fork of it: after install you will be in a 100% traditional GNOME environment. All the apps included are forks of the GNOME 2 apps, from Nautilus to gedit and eog. They have the name changed so they can live together on the same system. What will happen when the major GTK+ apps will move to GTK+3 remain to be seen, but that's distant future anyway.
If you want to pretend GNOME 3 never happened, then MATE is for you. That is its intended audience.
Even if at this point it is vaporware, GNOME developers announced a "Classic" mode, it's going to be a set of extensions on top of the shell, giving a more traditional feel. This is not Fedora material, is just a proposal. When/if released we'll see if it is too late and/or too little, for now it looks mostly like a move to limit defectors.