This paper reports on extensions to a decision-theoretic location-aware shopping guide and on the results of user studies that have accompanied its development. On the basis of the results of an earlier user study in a mock-up of a shopping mall, we implemented an improved version of the shopping guide. A new user study with the improved system in a real shopping mall confirms in a much more realistic setting the generally positive user attitudes found in the earlier study. The new study also sheds further light on the usability issues raised by the system, some of which can also arise with other mobile guides and recommenders. One such issue concerns desire of users to be able to understand and second-guess the system’s recommendations. This requirement led to the development of an explanation component for the decision-theoretic guide, which was evaluated in a smaller follow-up study in the shopping mall. Keywords Mobile commerce, navigation support, decision-theoretic planning, u...