I am actually surprised DirectBET has so many votes.
Direct Dice is popular because it features no house edge for frequent bettors.
It's the only provably fair dice game out there that is favorable to you, the players, because while having fun and betting with no house edge, you're actually freerolling on the 10 BTC Jackpot, that is provided on the house !
For more details :
https://bitcointalk.org/index.php?topic=743577.0and i am still surprised to see that pd is behind direct bet!
According to me pd is way better than other sites in terms of service provided , design and game.