A bit about Fedora
The code and sponsoring that Fedora inherits from Red Hat give it an edge. It's one of the few Linux distributions backed by a large company (one with higher stock prices than Microsoft, even), which gives it a definite edge over its competition. Even with this backing, it doesn't go closed-garden (ala Canonical's approach) and still has a positive sense of community among the developers.
Fedora 17 was an incremental increase over Fedora 16. Very little was improved, and it felt like all that had been done was some user experience fixing and the package freeze. Fedora 17 doesn't deserve to be in the same ballpark as Fedora 18. Fedora 18 was an enormous improvement, and an obvious display of effort from all parties involved (especially Gnome and the Fedora core development team). Here are some reasons why:
Paraphrasing Linus Torvalds, "Gnome 3 is a nightmare". If only he had tried Gnome 3.6.2 before that statement. It has animations (like Cinnamon) on by default, a working extension system, and features to maximize the screen space used by windows (like removing Window decorations on vertically maximized windows). It also has a new lock screen that tablet and touch users alike will find useful, and desktop and laptop users may find amusing. The buttons are even noticeably more aesthetically pleasing.
http://www.extensions.gnome.org/). It's worth adding that the Gnome applications have added features, like EXIF data examination in pictures via Eye of Gnome, and a new virtual machine application called Gnome Boxes (a Qemu frontend).
It would be unfair to talk about Fedora without mentioning the work that the Fedora developers have put into the operating system. The installer, Anaconda (which previously left a bit to be desired compared to Ubuntu) has had a visual and feature Facelift, supporting partial encryption and advanced partitioning. I was displeased with the layout of some of the buttons on the installer. You might have to hunt around for a button on the "root password" section (which, by the way, is in a weird optional part of the installer) in order to save your changes.
Firefox - 17
Gnome - 3.6.2
.iso is 942 MiB large
As of 1-17-12 the initial yum update is 270 MiB downloaded, 7 MiB disk space used on Gnome.
The best part of a review is the opinionated part. The part where feelings are scarred and lines drawn. Here are my opinions about Fedora 18 and Gnome 3.6.2.
The installer needs work, but it's much more user friendly (especially aesthetically) than it was beforehand.
The user experience is mind-blowing. Fedora is trying hard to cater to the end-user while not sacrificing any of the 4 essential freedoms, even where it would make life far easier.
Resources and Security are as good as always, and better with CPU cycles.
Gnome has surprisingly good defaults, and nice home-brewed applications.