After following this project for neigh on three years (and participating in the multiple betas), I can say that this game meets my idea of the ultimate merging of old school and new school D&D by way of a 2e core with a 21st century polish. If you played 2e (or even 1e or Basic) this game will feel very familiar but also fresh and new, this would also be true if you played any later editions. The cool thing is many of the different features are entirely optional, just like 2e, but they can be turned "off" without causing problems in the game- you can make it very simple or a bit crunchy (just a bit).
If you have any AD&D material this game will run it with minimal tinkering (on the fly). Newer generations of players will not stumble on the mechanics either as they might with roll low/roll high, matrixes or thac0. As C&C is to 1e, Pathfinder is to 3.5, Myth & Magic is to 2e.
Modern mechanics, flexible playstyles, compatible with older material, options for players, grid 100% optional. Maybe Wotc should hire these guys :p
The free Starter Guides can give you a taste and spin.