Your experience differs from mine. If I only count major incidents, I've had at least two occasions where a Linux operating system update completely hosed my system. One was a Rackspace VPS I never managed to recover, I had to use their management tools to download a binary image of the unbootable disk and fuss around to mount it and get my files off so I could build a new server.
I'm very hesitant to touch Linux updates, but I am occasionally "forced to" when I need to run a new piece of software that ends up being like pulling on a loose string on a sweater.