Read Monte Cook's blog. There's been a LOT of details released.
What interests me most about the game is mainly the setting and after that the system.
The setting is on Earth approximately one billion years in the future. It's called the "Ninth World" to indicate that many civilizations have risen and fallen in the past one billion years. It is science fantasy. At first blush, it looks like a fantasy game and setting with a medieval level of technology. However, instead of magic, there are remnants of advanced technology from the past civilizations, tech that is far beyond what we have today.
The system insterests me too, though I've seen less detail on that. What I have seen that I like is that the mechanics take a back seat to the setting and characters. The rules of the game are described in a couple of relatively short chapters in the book. The focus is on fun and story, not crunching numbers or going through endless charts. I'm really hoping for a system that you can just run on the fly and never have to look anything up.
Going by Monte's work in the past, I think it's fairly safe to have high expectations!
As to supplements, I'm sure there will be. That is how a publisher makes money--publishing books. However, such supplements are never required for any game, and certainly won't be in one where the system is simple and streamlined.