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- Speech based interaction alone may be inefficient for users who use the system very often. The fact that the system asks the same questions can become irritating after some point.
- Nevertheless, the targeted user group is elderly people for whom physical manipulation often may pose additional challenges. From this point of view the interface is considered efficient.
- The interface combines speech and touch which allows to delegate problems that would be difficult to solve with speech only to a touch based interaction. For instance, In order to get additional information about an object the user needs to tap over the object. Another example is that the system records a history of spatial descriptions that the user can scroll through because memorising all the location is not feasible.
- Difficult to convey which statements will work. To help the situation the system asks questions that prompt one word response, such as "Name the first landmark" or "Name the start of the route". The system also provides and animated graphic representation of the expected input.
- Generating an animated video of a route can be very time consuming.
Safety
- The weakness of the system is that there is infinite number of speech commands that users can try.
- The interface improves safety of the system by making it to ask questions sequentially and in case of noisy input ask additional questions that help to disambiguate input.
- Generating animated videos of the route can be time consuming, therefore, there is a risk that users can get impatient and start tapping the screen or giving additional commands.