Considering user interface friendliness, graphical beauty and technical maturity, I have no doubt, Ubuntu is ready. I have seen many people using Ubuntu and love it. Speaking about non-technical users, the most notable thing they usually have in common is a person that told them about Ubuntu and helped to get it running. They were initiated by someone that is in some way close to them and this person took the first steps of informing, installing and offering some kind of support at the very beginning. I have also heard many stories of people who decided to dive in by themselves and had troubles.
I first got interested in Dell computers when I saw on the Ubuntu website that Dell sells computers tailored for Ubuntu with the operating system pre-installed from factory. For me, personally, it was a reason to believe that I would finally have a computer that has a hardware entirely compatible with my software, beautifully integrating the features of my software with the capacity of my hardware. Surprisingly, is seems that sometimes innovative companies decide not to innovate any more...
With Ubuntu you can choose to update your system every six months or every two years if you stick to the "Long Term Support" versions. This option is in the "Update Manager" under Settings > Updates > Release upgrade.
Ubuntu was made with one priority: being user-friendly. It's not by chance that their slogan is "Linux for human beings". The most important factor of Ubuntu's success is the ease of installation and configuration. No technical knowledge is required to have it up and running. The choices of standard applications are good and they are well integrated into the operating system as a whole.