"How do you tell if someone uses arch linux? They will tell you." (c) Reddit
I switched to Arch after discovering that most issues I googled are described and solved either in Arch Wiki or in Arch forums. The wiki, although sometimes opinionated and biased (towards "elitist" part of society), is great way of discovering more about Linux.
My conclusions after using Arch for 3 years, both on laptop and office machine:
1) Yes, the manual installation is a pain, but after doing it at least once you will know how to boot from CD or pen drive to mount and recover your broken system (and how to chroot to it to fix). It saved me several times, even with other distros. Also, it gives interesting insights if, for example, you want to get full-disk encryption.
2) Yes, Arch always has latest-and-greatest, and, since I love to binge through Linux and OSS news (began doing that before using Linux), it's very cool to read about new release of your favorite %package% and then use it in a week or two. Also, since I'm web developer, I'm able to prepare my websites for latest Apache and PHP way before they are included in current Debian or Ubuntu which my servers run.
3) Arch is about a choice. If you love reading, choosing, trying something new, tweaking and tinkering - it's ok. If you don't like to spend time toying - it's ok too, but, IMHO, you're missing the fun. If you want something to "Just work", go with Fedora/Debian/Whatever.
4) Package management (pacman) is great. Once I updated 32-bit system to 64-bit without any issues (aside from forgetting to install 64-bit kernel to bootloader). Another time I borked attributes of the whole filesystem, and was able to fix everything using pacman.
5) Yes, things do break with updates. Especially when you combine them in perverse ways. No, I won't install it on the server. (Although some people do)
6) After Arch, I began to much better see and understand the common parts and the differences between different distros. I even stopped to be afraid of Debian Sid ))
P.S. First distro I installed was Slackware. But it was in 2005, and turned out to be so difficult to use and maintain, that I returned to Windows for 3 more years until successfully switching to Ubuntu 8.04.