I've been using Linux for longer than I care to remember (and 386BSD before that) and after a few years on Ubuntu I was amazed at how much of a breath of fresh air Arch is.
Ubuntu always worked well compared to other distros, I could do stuff and it'd just work or there'd be plenty of help and support. I put Arch on an old P3 850 with 256mb of RAM and it just flies. I can be logged into my desktop from cold boot in the time it takes for my dual core Vista laptop to go from login to desktop. That (and discovering awesome wm) are the reasons that Arch gets my vote. Yes there's a learning curve as with any new distro or program but it's definitely worthwhile.
I've only been using Linux for half a year, maybe, and in that time I've tried Ubuntu, Gentoo, and Arch. Gentoo will always hold a place in my heart for teaching me more in three days than I learned in three months on Ubuntu, but maintaining it was just more work than I wanted to put in for my primary use machine. It also has the best community I've found--any question I had was already answered, in depth, on the forums. Ubuntu and Arch seem to have too many people guessing at answers instead of knowing them, from what I've experienced.
I've been consistently impressed with the Arch philosophy and implementation. Pacman's a dream to work with and the AUR/ABS is a beautiful system.
I love Arch. They've done a great job straddling the line between minimalistic and easy to use. It reminds me (in a good way) of how Linux distros tended to work many years ago.
