What the scariest zombie movies do is build suspense, keeping a tight knot in your stomach for the duration. The Walking Dead certainly did that. Whether Grimes was walking down a dark staircase, or approaching a city known to be dangerous on a horse, my adrenaline never stopped pumping. The danger element was ever-present, and camera angles frequently kept the wide shot a mystery, making things seem even more precarious.
The camera work was spectacular. AMC is known for making beautiful-looking shows. Blood, guts, and gore don't really count as aesthetically pleasing, but the landscapes were nice. And each shot was executed with care and precision. The pilot felt so well made, I couldn't help but be pulled in. Certainly, even if you are not a zombie fan, you can appreciate elements that fall into place with such care?
The biggest question is, are zombies ripe for a series, and will fans keep tuning in week after week? I believe the audience for this type of show is limited. Plenty of people can't stand the genre, and few non-zombie fans (except, perhaps, myself) will be drawn into the premise. It will never reach a super-wide fanbase, but zombie lovers have bought enough tickets to sell many a movie, so perhaps they are abundant enough to sustain a weekly television show.
I can't imagine The Walking Dead will not appeal to the zombie-philes. All of the traditional elements are there, in such rich detail. The pilot felt like an R-rated movie, with so much gore I couldn't believe I was watching basic cable. This is what they love, and so, as long as they can find it, there'll be some fans.
A huge part of zombie stories, though, usually involves most of the main characters being picked off one by one. Here is where The Walking Dead has to be careful. Yes, characters have to die in order to keep interest and the sense of impending doom strecthed out for many installments. Yet, it would get old to keep finding new pockets of survivors. In this case, important deaths will need to be doled out slowly, not allowing the body county to rise swiftly. The longer the show goes on, the more attached viewers will become to their favorite characters, and each death will carry a risk of alienating fans of a certain actor. But if death is not a regular part of the show, more will tune out because the series will seem too tame for zombie fans.