One of the things I miss about book!Aziraphale is how much of a bastard he is.
Don't get me wrong. As anyone else, I'm utterly charmed by Sheen's performance and I got everything I wanted out of the show, but there is the problem that when Crowley says 'Enough of a bastard to be worth knowing', and Aziraphale smiles, it rings hollow. Because show!Aziraphale is an absolute sweetheart.
What we lost in the translation are the nasty parts of Aziraphale character, starting from the very beginning. "I'm an angel, I can't possibly act bad" is a dangerous idea to live with, and it shows.
On paper, Aziraphale is perfect. He loves people... They just have to stay away from him, because they're an inconvenience. In the book it's implied that he gets rid of the most pressing customers, and we don't know how. They just disappear.
He loves animals... But if he accidentally kills a dove because of his incompetence as a magician, it's not his problem. (And he doesn't care enough to keep his animals in a safe place, which is also telling). Crowley resurrects the dove. Crowley.
He loves to collect rare religios texts... But the wrong ones. The ones that contains sentences as "the unrighteous shall inherit the Kingdom of God", or "thou shaft commit adultery". Those nasty bits are the ones that amuse Aziraphale.
He does miracles... But when Crowley turns the water pistol into real guns, nobody's hurt. When Aziraphale turns the real guns into water pistols (at Warlock's birthday), he misses one. He hears a shot in the distance, and he doesn't care enough to come back to check.
Of course, Aziraphale tries actively to do good. He's pleased when he heals Anathema (and her bike). But. Anathema was a 'Good Samaritan' Textbook Example, so close to the Bible that there could not be any possible doubts about what the 'right' course of action was supposed to be. Anathema was easy.
Adam wasn't easy. Which is why in the book Crowley doesn't have to convince Aziraphale to kill the antichrist, because Aziraphale thinks that he's the antichrist, so killing him must be good. And even if Aziraphale falters when he sees the kid, the fact that he has lasted that long without questioning the goodness of his actions is telling.
In conclusion, I miss book!Aziraphale, the real bastard of the duo.