Debian is the only linux distro that has been able to manage an unbroken line of upgrades working across systems for many, many years. No other distro that I'm aware of has been able to do this without botching upgrades to the point that a reinstall was the only option left. That, and it's governance model and staying true to their mission are all major accomplishments.

It's a pity that Ian Murdock did not live to see his brainchild become 30. I owe that man a lot.