Our ds' elementary school didn't use Everyday Math, but used a similar curriculum (our school district uses EM in the neighborhood schools, ds was in an optional school). DS is a total math kid, but did *not* like the spiral-ness of the curriculum and found it boring. I think if it had been implemented in a situation where he was able to work at his ability level and move through the units at his own pace he would have been ok with it.
The school he's in now uses Connected Math, and fwiw, ds likes it a-ok and there are things that I like about it (and I'm a total math geek with a math degree who does not like EM!). The school ds is in now ends after 8th grade, and the kids who move on to our districts gifted magnet program for high school have to test back in for math placement... and fwiw... it appears from what I've seen so far that it's not curriculum that matters as much as... the teacher. I've also found that even though ds' school does not accelerate for all subjects, he has done well and really enjoyed some of his non-acclerated subjects even though they are slower-paced than he needs... when he has an inspiring teacher. So that would be what I would probably spend more time thinking through and researching - what do you know about the teaching staff?
Best wishes,
polarbear
