This article presents a case study, in which ChatGPT has been integrated into the writing assignment of a course in a Dutch university whereby the students co-wrote an essay with the AI-powered chatbot, ChatGPT 3.5. We examined 1) how the students used it, 2) their experienced challenges and benefits, 3) their view of its responsible use, and 4) their perception of skills required for the effective collaboration with ChatGPT in the co-writing process. Based on the analysis of students’ written self-reflections (N = 43), the results show that the perceived benefits and challenges are associated with different types of uses of ChatGPT. We found that some uses of ChatGPT, namely for content generation, present more challenges to the students than others. We also identified a set of skills that the students perceive they need, to use ChatGPT effectively: critical thinking, creativity, fact checking and evidence gathering, collaborative writing, ethical awareness, and effective instruction of ChatGPT.