4D ultrasounds

Amber • "Be who you needed whenever you were a child."
I went for my checkup today, and we've finally got a 4D ultrasound set up for June 17. I've heard some say it isn't wort it, and others say it's totally worth it. So, my question is, have any of you done a 4D ultrasound and find that it's not worth it, or find that it was definitely worth it. If you've have one done can you post pictures? I'm just interested in how they'll turn out. Also, if you can give advice on how to prepare for it, I'd love to hear it.