The use of two-dimensional (2D) and three-dimensional (3D) visual displays for discrete-event simulation (DES) has become very popular within the simulation community in recent years. This paper presents results from surveys of users of 3D and 2D simulation applications regarding their views of the impact, benefits and drawbacks of 3D displays. The results indicate that 3D displays can often be more effective than 2D displays in communication, verification and validation, and experimentation. This can lead to a better project outcome with an improved understanding of the real system and a better solution for the decision maker. The main drawback is the additional cost, time and complexity of building the model. Potential implications for modeling in general are the importance of being able to relate the model to the real system and of involving the decision maker in the modeling process.