I'm an Army 89D in Iraq currently. Here's what to expect from the EOD course: a LOT of tests... tests where one mistake means "try again tomorrow".
But they're all passable. I got through it and now I'm in Iraq having a lot of fun doing a great job.
They'll constantly tell you that the tests are set up for you to pass, and that's true. I didn't believe it at the time, but in retrospect, it was completely accurate.
As for attrition rates: it's pretty high. But you quickly pick out those that aren't going to make it. Study with the people who you think ARE going to make it and you'll be fine. My class started with 28 people, and we graduated with only 3 of the original people.
Hope this helps.