I didn't make it to the tourney (stayed up way too late the night before) but one thing I was afraid of (and rightly so, as the decklists showed) was that it would be perfectly possible to make a 'monowater' deck with two pillars/pends of some other random element and satisfy the deckbuilding requirements. Heck, for that matter, a 58 card monowater with two other pendulums would've been legal, or even something like a 60 card nearly monofire with 6 nymph's tears, mark of water, and two random pendulums. (though probably not actually any good, but admittedly circumventing the intent of the rules).
I did, however, absolutely love the idea of an alternate win condition, in this case, the having the four different nymphs in play. I'd like to see more of that kind of thing in the future. There are all sorts of possibilities, like having six voodoo dolls in play, a creature with 100hp, if opponent's life ever hits exactly the numbers 13, 26, 39, or 52, they must concede (no idea what kind of sense that would make, but just to show what's possible), have a leaf dragon with 10 attack, etc etc.
I didn't build any decks for this tourney, but the ideas I had were 1) basically deuce's squid deck, 2) air/fire/water deck making blue nymphs for gas, 3) life/earth/water deck making life nymphs for rush and auburns for stall, 4) water/light/time stall with lots of healing, sundials, draw, etc, 5) water/light/aether stall with dims and healing and stuff, 6) water/light/aether/time stall that combined 4&5, 6) basically pure NT rush but with two other random pendulums to make it legal.
Also, I'm kinda surprised that lobotomizers didn't make it into more decklists. They're really good against nymphs :p
edit: NM; lobotomizer banned. mystery solved.