I don't know much about Everyday Math, but I rarely hear a teacher say "I love it". I have, however, encountered many who say "I hate it". From what I understand it's a spiral approach. How I've had it explained to me (not sure how accurate my memory is) is that there are many concepts thrown out at once - not one whole unit taught on this concept, and then another unit on a different one. If they don't get a concept the first time, your teaching will spiral back to it later in the school year. Some teachers I've spoke with say some of the concepts they need to teach early in the year, the kids just don't seem developmentally ready for them.
We use a math book, in conjunction with Investigations. We have an older edition (about 5 years old?) but I've heard wonderful things about the more current editions. With the old one, we found lots of holes where it didn't hit on all of our GLCES (standards/benchmarks) so we willed those holes in with our math books. Investigations is very hands on, and encourages higher level thinking through journaling, partnering, etc. The games are fun, but they really drive home the concept. There isn't a WHOLE lot of prep work that goes into playing the games (getting and gathering materials) BUT, our edition (could be different now) isn't all that teacher-friendly. LOTS of reading and trying to pull it all together before teaching a lesson.
I like the balance we have with using both - but would LOVE to hear about the newer Investigations...