vtec96, they release a iso install every so often so once you get arch base installed theres not a massive upgrade. However once installed, you simply update as often as you can, once a day is decent.
If your farmiular with ubuntu, you have apt-get update, apt-get upgrade. arch has pacman, pacman is very quick and is simply to use. Pacman -S firefox will install firefox, pacman -R will remove firefox. pacman -Sy will "update" and pacman -Syu with "update and upgrade". Pacman has no gui by default but there are some that people have made if you want it.
As for updates, like ubuntu (i'm aways comparing to ubuntu because im assuming you have used it) you will get general updates to programs, security fixes, but this happens all the time, as i said, you will never have a huge 800mb download to upgrade to the latest version, unless you dont update for a while, which a bit like gentoo above isnt advised.
The install isn't as hard as the wiki makes out, partly because the install has been updated a lot, and theres no cmd line as such, you just need to edit a couple of files with nano. Once you have the base installed, the wiki will tell you how to get sound etc working and give you a big choice of GUIs to install and how to install them, kdemod is only sligtly different in the fact that you need to add it to /etc/pacman.conf (i think thats it). I'm pretty sure it tells you in the wiki. You will want to use the beginners guide as it will get you installed and still tell you enough of what you should know about arch.