I think that the CC *can* be a huge improvement, in spite of having some math concepts now taught in 3rd or 4th, say, being moved to 5th. When I first heard that I was thinking, "oh my gosh, it's already too slow - this is a nightmare!" But, if it really, truly does go deeper not wider (I know, that phrase probably seems meaningless we've heard it so many times)... well, I'm willing to withhold judgement.
The standards don't spell out how deep is deep. Because of that, all is smoke and mirrors until the curriculum is chosen.
I haven't seen the new EM as redone for the CC. My experience with the previous version, though, is that providing differentiation was very difficult for teachers.
As far as I know, our elementary school hasn't chosen a new curriculum. The middle school one is achieving this "deeper, not wider" for kids through making it almost entirely online instruction, spelling disaster in our house.
