What's interesting is that they are in part re-creating the original problem they were trying to solve.

The complaints about Debian were that they only cut a release like every two years. The Debian response was that people who wanted more timely updates could run the "testing" branch, which was a "rolling" release.

Ubuntu promised to solve the slow release cycles and the instability of a rolling branch by cutting stable and well-composed releases on a rigorous six month schedule.

This announcement sounds a lot like the original Debian model they were trying to get away from.