1. The writers. Always the most important part of any show. You can have great actors, but if the writing component isn't there, the series falls apart (alas, I'm talking to you, Pan Am. You SHOULD have been good, with Christina Ricci and 60's air stewardesses all, but - BOOORRRING!!!)
2. The characters. Terrific actors are very important. Connie Britton's take on Vivien Harmon is my favorite of the bunch, although she has some stiff competition with Tate , played by Evan Peters, and Taissa Farmiga as Violet, Vivien's daughter. In fact, Farmiga's depiction of a troubled, intelligent high school girl is one of the most amazing performances I've seen in a while.
3. The opening music. And sequence. Watch it and you just know that the show is going to be seriously creepy. Disturbingly so, in fact.
4. No holds barred. Those amazing writers happily take on gay relationships, the Black Dahlia, current anti-government sentiment, and even the current state of the housing market, and do so in a way that is completely fascinating. And creepy and disturbing.
5. Dylan McDermott's butt - Not a huge Dylan fan, but he is showing some serious acting chops here, plus he has no problem showing his butt off. A lot.
No, I'm not going to put up an image of that here. It's Fresh Pot of Tea, after all, not Large Bottle of Jack.
If you enjoy ghosts and horror fiction, then check the show out. Be prepared for adult content and some jolts to the system. (Did I mention creepy and disturbing?) But I haven't seen scary TV like this in a while.