I know season 1 is on Netflix instant watch, not sure if other season are or not. I wasn't sure in the beginning if I would keep watching, but I'm so glad I did. Rumpelstiltskin/Mr. Gold/The Dark One has to be one of my all time favorite villains. And Regina/The Evil Queen is as beautiful as she is evil. The show has a pretty dedicated following and I'm sure quite a few would recognize any patterns from it.
They are coming out with a spin off which will take place in Wonderland with Alice. I try not to get involved in too many T.V. series, but I think this will make my list.