First and foremost, people watch The Walking Dead for the zombies. There's something about them that frightens and intrigues, as they slouch along the ground, hunting for human flesh. When zombies are on screen, The Walking Dead is practically unmatched in terms of tension and I think the high ratings for the first season can attest to that.
However, it is a television show where characters are supposed to be integral, and thus far they've been more distractions between the zombies than anything else. Most of "What Lies Ahead" is spent on the characters instead of the zombies, trying to balance the two and it doesn't quite work completely. We get introduced to new dynamics--Carol angry at Rick, Lori mad at Shane for ignoring Carl (and not for the attempted rape incident?), Shane planning on leaving, Andrea being mad at Dale and wanting to leave with Shane--but I'm not sure I care about the characters anymore than I did before. None of the character work seemed particularly significant.
Beyond the characters, there was plenty to like about the episode. The zombie herd coming down the highway was fantastic, easily matching the zombie attacks from the first season, including the pilot. Even though there aren't zombies throughout the episode, there is still plenty of tension. There are long stretches of silence, an uneasy stillness, which permeates each scene. The lack of zombies indicates something potentially greater than a zombie--that a zombie can be hiding around the next corner.