I don’t like Proportional Representation because it widens the gap between ordinary people and the people who are supposed to represent them. It does this in several ways. First, it hands more power to the party hacks who compile the lists. They can make it impossible for people to vote out someone they don't like. Second, on all the evidence, PR gives more power to smaller parties, who use it irresponsibly. Third, many ordinary people simply can’t understand complicated PR systems, such as New Zealand’s Mixed Member Proportional system.
But most of all, I dislike PR because it institutionalises the corrosive assumption that a Member of Parliament can represent people only in their capacity as voters for a particular political party, rather than as citizens with interests beyond party politics. It's an assumption that entrenches widespread cynicism, because under PR Members of Parliament they can hardly be expected to question the party line: their party is after all their only imporant qualification for being an MP at all. Under PR MPs see it as their duty to represent only the people who voted for the party that employs them, and I think that's worse than what went on under first-past-the-post, where there was a hope, even an expectation, that Members would act responsibly on behalf of all their constituents. The theory and practice of PR entrenches the worst aspects of party politics.