I noticed the same thing about Genesis 3 some time ago--and I thought I was the only one! I'm so glad to see someone else noticed it, too. Basically, Satan told Eve that if she ate of the tree, three things would happen:
(1) She would not die;
(2) Her eyes would be opened and
(3) She would become like God, knowing good and bad.
If you read through the account and into Chapter 4, all three things that Satan said would happen actually happened, and the account even uses the same words. She did not die, but lived on for another 900+ years. Her eyes were "opened," with some kind of increased consciousness and/or guilt (whatever it actually means, it happened, according to the account). And then God says, "Here the man has become like us..." and so make sure Adam and Even DIDN'T eat of the tree of life and live forever (which means that was still a possibility, even in their supposedly sinful, fallen state), God takes proactive steps to remove them from the area.
JWs call Satan a liar--even Jesus called Satan the Father of the Lie--but my question is: What did he lie about?