I'm not saying the characterization is fantastic in the comic, far from it, but they're established pretty clearly early on. From the first chapter I already knew what kind of character Rick was, and the way they handeled Morgan in the book was simple and straightforward. I agree, characters should be developed over time, but right in the first 10 minutes of the pilot it's clear Shane is a douche and the writers tried REALLY hard to drive this point home. It was insulting how blunt the exposition was, where in the comic at least there's subtlety and build-up.
Something I love in the book was that the opening scene started right away with action, ended abruptly and threw you into the middle of the situation just as Rick had been. In the show we have a zombie child picking up a stuffed animal, a drawn out, pointless conversation, and a boring, tensionless shootout filled with completely superfluous characters. The exact same information the pilot took 20 minutes to reveal could've been transmitted within a minute, but instead we get endless scenes where absolutely nothing happens.
I'm not trying to sound superior here, but most televisons shows don't impress me because the writing is marketed to the lowest common denominator. Nothing is ever illustrated with any grace or tact, it's all just tied into a bundle and shoved down your throat.
