[Book Spoilers] The world hates Theon

[Anwar]

They did eliminate some of Theon's nastier/annoying qualities in the TV show: When they're executing the Deserter instead of smiling the whole time Theon is as solemn as the rest of them and takes no pleasure from the act, and he doesn't kick the guy's head afterwards.

Also, Jon doesn't voice his disgust of Theon (calling him an ass) and they seem to have an okay relationship and get along fine together (at least there's no hostility between them whenever we see them together in the first two episodes).

And TV Theon doesn't have the "Smiling like a smug jerk" look we're told the book version does. He comes off as a more serious, dutiful character all-around than the book version.