Considering that they have LTS versions if you have slightly older hardware (12.04 is supported for 5 years), you aren't forced to upgrade.

I've been using Ubuntu since Breezy and every upgrade I haven't had a problem. I use it on many of my machines (apart from my laptop due to Bumblebee) and have had no issues with the 6 month updates, but I usually stay on the LTS versions.