I don't own one, but joined a gym for the first time five days ago, and the elliptical trainer is kicking my butt harder than the actual personal trainer is.
Clint or I can't even move today, we're so sore. And I wish I had known they were hard on your back. I picked the elliptical over the treadmill because I can't run long distances due to arthritis in my hip (at the age of 28!), but I've noticed that my low back is really really hurting tonight.
I do think that I'm getting a good workout from it. I only can do about 10-15 minutes right now...I am so out of shape.