This is one of the biggest applications of the concept of flat design is in mobile devices such are smart phones and tablets. The release of the Windows Phone and Windows 8 interfaces and Apple’s IOS7 are good examples of this.
The advantage here is that the interface that you see on your device is simple and less complicated than before and maybe less scrolling. Links are typically a bold button, some with an arrow attached, or just intuitive graphic like a house icon for the home page. These encourage you to click on them and take your to the next page on your journey around the website.
The disadvantage however is that some users may not be entirely comfortable with the interface and, according to the Norman Nielsen Group, not always know where to click or tap if it is not clear to the user what they should do. This has been illustrated by users of Windows 8 have had a terrible time adjusting to the new interface and were lost without the iconic “start” button or the Windows icon on the bottom left of the screen.
Flat design also tends to minimize information density, that it the amount of information presented in efforts towards a simple design.
Flat design encourages the use of many colours and to some breaks away from the typical web safe colours.
The advantages of this is this creates a more contrasting interfaces such as a background colour to a link to a new section of the website being very different to the one before it and after it.
Also bright and bold colours are seen as engaging, warm and inviting.
The disadvantage is that the more colours uses in a project the harder it will be to match them properly. What is this means is that putting good colours together for a good looking interface. Designers who make successful uses of colour use a system of consistency in terms of colour saturation and brightness so that the choice of colour looks intentional.
Flat design has brought about the focus on type. That is using decorative type and different font types.
The advantages of this that typography has blossomed once again and shown how good it is when used in this design concept. Gone is the decoration uses with fonts like shadows or extra boldness.
The disadvantage is that while the focus is on good typography, equally bad typography will stand out. For example, the ultra-tin type used in the Apple IOS7 interface was heavily criticised. Flat design is also unforgiving when it comes to the use of bold. However, every choice has its consequences whether these are big or small.
Flat design encourages sharpness and a clean looking interface.
The advantages are that a lot of high contrasting features such as colour, typography and an overall boldness present a look that is easy to follow. Buttons and other user interface elements are in many cases made using shapes with basic rounding for corners or edges. For example a home icon in a website may be illustrated with a square or rounded box with a house like icon inside.
The disadvantage is that an interface can look too simple. Some experts agree that it can be very hard to convey a complex message using this concept. Also, advocates of skeuomorphism say that embellishments such a bold underline or a slight shadow under a button add a sense of realism to make an interface easy to use. This does depend on the project.
Flat design has the advantage of placing constraints on the designer to stay within the style being used and avoid irrelevant things like shadows and animations or effects that actually have not place. This is also known as minimalism.
The disadvantage however is that designers are limited to what they can use to make a design truly flat and as above some skeuomorphism is not a sin if used lightly.