I loved them as a kid. They were a great thing to do with my mom. She loved the holographic ones--I remember we had a huge holographic underwater one that featured dolphins. Those are really fond memories.

I should pick puzzles back up again--watching my boyfriend play Kingdom Hearts 2 and collect pieces and reassemble the puzzles has been surprisingly great. I love the process of sifting through pieces to find end pieces, and steadily drifting inward from there.