If this is your first time here, it can be a good idea to first read my general post about distrohopping.
Among the people using the Distrowatch site, Linux Mint has for some time been the most popular GNU/Linux distribution, passing the long time favorite Ubuntu. Other varieties of Ubuntu comes quite high on the list, and there are probably numerous Linux and Ubuntu users who does not visit Distrowatch, so I assume Ubuntu et al is still way ahead on the desktop in total number of users. The main Mint (now version 13, called Maya) is based on Ubuntu, like many other distros. There is also the Debian based one (LMDE). Mint is a well-established, but still rising star. I used and/or tried some different Mints a year or two ago, and found them very polished and easy to install and use.
Installation is straightforward. Default applications are the common ones for a GTK based desktop environment: Firefox, Thunderbird, LibreOffice, Pidgin, Brasero and quite a few others. It's a perfect balance between having good programs for common tasks, and not installing loads and loads of them, that some distros seem to do. Honestly, it is nice when an install image isn't like 3 GB or so. Huge installers on DVD are good to give to users with small bandwidth, but otherwise not so great in my opinion. A more unusual choice in Mint Cinnamon is Banshee as music player. Banshee works fine, it uses Miro for podcast search, and has Amazon store built in. It does not have by default have plugins for freer music catalogues such as Jamendo and Magnatune, which to me is a miss. Mint does not claim to be a fully free OS, and free software and free culture are not equivalents, but giving people chance to discover CC-licensed and freer culture should absolutely go with GNU/Linux, in my opinion.
Cinnamon comes with IRC client XChat in default install. When I started it, I was automatically logged in with my user name (the user name in my install) into the Official Linux Mint Support Channel (#linuxmint-help) and Mint Chat (#linuxmint-chat) on irc.spotchat.org. Nice touch, but a bit surprising, and maybe confusing for someone who never have used IRC. Or maybe it is a nice introduction for an IRC newcomer. Grabbing my user name to log me in felt in all honesty a bit strange. It is very common to have support channels on IRC for both distributions and single software projects. Just remember to try find solutions on web, e.g. forums for Mint or Ubuntu. Please try read and solve problems before spamming questions. Support isn't paid for, so please do not take up others' time unnecessarily. There are a lot of helpful people, but do not over use them.
Cinnamon is the absolutely best GNOME3 based desktop I have used. It runs smoothly and it looks very nice (well, that is a matter of personal taste of course). The settings are simple but not too simple, and there are extensions that can be downloaded from within the Cinnamon Settings. The menu is simply great. I usually do not like multi-column menues (again that is just me), but the one included here is really good. While others always seemed to me like roundabout ways of navigating, and taking up too much screen space, the Cinnamon menu I just enjoy. The Cinnamon panel with menu, task bar and systray is really nice. The sound applet is the best I've ever seen. In general, a great attention to detail.
Cinnamon ran fine even with the free graphics drivers installed by default. The installation of the proprietary nVIDIA driver was simple. It is the stable version (at time of writing 295.xxx), and I haven't noticed any glitches after using it a while every day for maybe two weeks.
On the whole, a very pleasant experience. I definitely would recommend it for the newcomer to GNU/Linux. Cinnamon is a Mint project, but do not forget Mint rests on the shoulders of giants such as Ubuntu and Debian, GNOME and GNU. There is nothing wrong with that. In the free software world, there are many shoulders, and one can rest on them as much as one likes, as long as one respects the licenses and the users. Cinnamon is also available on a few other distros.