The keyring issue that other commenters mention has to be the dumbest misfeature ever, because upgrading is guaranteed to fail, yet nobody fixes it. To make things worse, one of the top Google suggestions is a pacman command that can cause libc to be upgraded without a full system upgrade, which will make your system unusable immediately. No process will launch after that. I had to do very desperate recovery steps when that happened to me. To be honest, I'm still not entirely sure how to safely fix the keyring issue when it happens.
Other than that, and this may sound very strange given the last paragraph, Arch is fantastic. It's the most usable and useful system for general software development I've ever owned. Basically, you follow the wiki, and everything just works, sound, graphics, wifi. I never had that with Linux, not with Ubuntu, not with SuSE.