This study investigated engagement with a DA for surrogate decision-makers faced with critical choices regarding neurocritically ill patients. Effective DAs that convey information and engage users are crucial for promoting shared decisionmaking. Our holistic methodology, encompassing questionnaires, interviews with retrospective think-aloud protocols, and eyetracking, underscores the need for multidimensional engagement assessments in high-stakes scenarios. While the small sample size warrants caution, the study demonstrates the value of mixed methods in generating rich datasets and insights to understand user behaviors and engagement. Future research should validate findings with larger and more diverse samples, refine the DA based on feedback, and explore longitudinal effects on decision outcomes. Conducting field studies with broader participant pools will further bolster generalizability and facilitate iterative refinements of the DA's design.