I find myself somewhat sympathetic to Pete; his family upbringing was clearly emotionally-constipated (look at all his super-formal attempts to express emotion). He's a jerk, but I find him oddly likeable.
Me, too. One of the writers made the same comment on a DVD commentary about how Pete was sympathetic thanks to Vincent's portrayal. More or less called him a sympathetic weasel. Talk about a character who was emotionally starved to death growing up. He's not so different from Don on that score, but Pete is so awkward socially I feel for him. He feels like such a fish out of water socially and professionally.