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Learnability: The QR code scanner is a popular technology in many mobile applications, so many users would recognize it. There would be a population of users who are not as tech-savvy and who might not know how to use a QR scanner.
Efficiency: The QR scanner would immediately pull up the restaurant’s menu so there would be fewer button presses for the user. However, sometimes QR scanners take a while to scan the code, depending on the angle and proximity of the code.
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Learnability: The scroll wheel is not a common interface, but it is common enough that it would be recognizable. It also follows a modified-Lazy Susan metaphor which might help some users. Users might not know that they are supposed to drag dishes into the basket; this is why we would include tooltips. However, the necessity of tooltips at all begs the question of whether this interface is learnable.
Efficiency: The scroll wheel is not always efficient to go through for each task. It presents an element of novelty, ; however, it can often be cumbersome when browsing for new dishes. Also, scrolling, dragging and then clicking can be a a time-consuming process. The two step process is an organizational feature which prevents the user from being overwhelmed by all of the menu options at once.
Safety: The scroll wheel can be less safe if users go through the two-step process because of a lapse. However, the two-step process also remains a check that sometimes prevents errors because users can preview sub-categories before moving on.
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Learnability: The shopping cart metaphor is sometimes good for users to learn that they are in the final step of the decision process. It can also be hard to understand that the basket is for filtering initially, rather than just viewing. Users would probably not know that they are meant to click on the shopping cart to reach this filtering stage. Again, tooltips could solve this problem but tooltips are an inconvenient way to teach a user how to use the interface.
Efficiency: The filtering mechanism is not particularly efficient in that it can’t allow you to apply large filters, and makes only small comparisons. However, some users might like comparing individual items at a time if they are between particular choices - which makes it easier for people who are indecisive between 2-3 items.
Safety: This mechanism is safe in that it requires multiple steps to get to this stage, and people can still choose what items they want to compare. A comparison is usually going to be determined, and not random. If the wrong dish is there, it can be sent to the trash can easily. Users can add as many dishes they want, and also compare as many decisions they want, without having to worry about the number of items they might have dragged into the basket..