Arch Linux is the best OS around and the most fun. You build your system the way you want it and in so doing you become more of a Linux expert (the wiki says you need to be proficient in Linux to use, but I find that the only
thing necessary is a desire to learn). With the rolling-updates your system can always be safely on the bleeding
edge -- unlike Debian Testing, etc., but you must go to archlinux.org to see if there is any intervention required;
if not you can run into problems.

I've installed archlinux on several machines and have made several vm's of arch (I've had audio problems with the vm's). Until this August (2012), installing was fairly trivial -- as long as you follow the begginer's guide on arch's web page. Currently installing is harder since there is no gui (they got rid of the gui installer), so it might be helpful -- if you are not fairly knowledgeable about linux and the command line -- to seek help from someone who is fairly skilled with the Linux OS and who is quite familiar with the terminal.

I disagree that the latest install cd is more difficult. The Arch Install Framework was nice, but now you get to install everything with pacstrap! Last few times I installed I thought it was exceedingly easy.

mkfs --> mount --> pacstrap --> chroot --> nano nano nano --> grub-install --> passwd --> Done!

Arch is often seen as a ricer's or hobbyist's OS, and I can't exactly say I don't fit that criteria, but it is still by far the best operating system I've ever worked with. It's very fun. It evolves to best suit your needs, the longer you use it, the better it tends to just fit you like a glove. I've developed a very thorough appreciation for open source software (with Ubuntu I'm not even sure I knew the meaning of the term).

I would recommend Arch Linux to anyone ready and willing to learn, if they want to invest a little energy into creating their own personal Linux Nirvana on their machine. It will make anyone very geek-happy (or hopelessly frustrated, depends on how open minded you are :)!