Judging from my experience this morning, it's easier than it sounded like it used to be. We've never been to WDW before, so I've never tried to book the breakfast before, but when I called this morning at 7am, I got through immediately and it sounded like it was wide open (the CM asked me, 'early, middle, late?' so I'm guessing most of the time slots were still available. It certainly didn't seem like it was about to book up in 2 or 3 minutes like people have said it did in the past.
That being said, I think it has everything to do with the new 90 day booking policy and nothing to do with the storybook breakfast. I think many people who are 'in the know' about this policy change are flying in under the radar.
Jamee