We've lived with Everyday Mathematics through the last six years of my son's primary school education.
It's a lousy way to teach arithmetic and basic symbol manipulation to the non-mathematically gifted. This means it's a lousy way to teach, since the mathematically gifted would be better off playing with Mathematica.
The interesting question is what makes it lousy. I've wondered about that intermittently, and I think I've got the answer.
The problem with Everyday Math is that it asks too much of the math teacher. Most math teachers are just a bit about average (yes, I'm mathematically gifted); Everyday Math requires a 75th percentile teacher to really work. So it fails.