PR review sucks because engineers often don't optimise their code authoring for it. When they do it's a joy.

PR review of agent generated code sucks because agents are, in my experience, very poor at authoring for review. This makes sense because the review process is not represented in the resulting code artifact which is what they're trained on. Agents are always producing much larger changes than should be in a single step, and often touch unrelated code with poor judgement of whether it should be included or not.