This paper outlines the results of commercial field trial of a multimodal (speech and GUI) platform using natural language technologies in a mobile environment. During the trial we compared the user experience of the multimodal interface to the user experience with a comparable application providing only unimodal (GUI) interaction. A key objective of the analysis following the trial was to understand the etiology of the difference in user experience with the two systems. Speech-only usage was used to complete tasks 71% of the time on average across all participants and tasks. The remaining 29% was distributed among GUI-only usage and multimodal usage. These results indicate that for input, the natural language speech was the major contributor to the increased quality of user experience.