Based on Debian. Debian does not know nothing about desktops and is always too late with fixing errors. It is a good and stable server system. Point.
Ubuntu is still an impatient version of Debian. Yes Debian is conservative. It is done when it is done, just like FreePascal which is also conservative (to the extreme, I would sometimes sigh) and with good reason: user expectation should not be ruined by plethora of bugs. It is already difficult to keep users in line.
(Knowing about new features and do not want to wait for thorough testing)