Perhaps we need to define perfect differently. Perhaps Eden was not stimulating enough, too boring, no challenges - perhaps Eden was not perfect.
I think it was more than that and that Eden was perfect. God gave everything and, in my view, reserved a Tree saying "please recognize Me in that, after I have given you everything, by not eating that which recognizes who is the one who created and gave".
Basically, they committed spiritual adultery and divorces themselves from God.
Thankful that, as in Hosea, their spiritual prostitution didn't stop God from pursuing the object of His love, mankind. He purchased them back through the Cross and His blood.
Another way of looking at it, we forget to be grateful for all that we have by looking at what we don't have instead of what we do. We see it playing out so often in every day living.
I have two cars, a computer, a home, enjoying restaurants and have food on my table but the rich people have more than I and its not fair. And then they become bitter at what they don't have instead of finding contentment in what they do.
(Don't want to sidetrack Eden with this example) - just thinking of a modern day application