More and more people are using smartphones and tablets as their main means of access to the Internet. Whilst you can make you site Mobile friendly, having a native mobile application allows you to interact with your user in a number of different ways you cannot with a website.
For example, It is easy to link to the users calendar, share contacts etc.

A recent survey by Deloitte survey found that:
Smartphones are becoming integral to our retail experiences – 13% of UK adults have now made a mobile payment in-store, 40% have made a mobile-commerce purchase with their phone and 59% have used their smartphone to browse retailers’ sites.

While the trends are all upward, currently just 1% are using their phones to make payments on a regular basis (see Figure 1). We expect that in a year’s time the proportion of phone owners who pay using by their phone in-store will increase further, and the proportion of those who do so regularly will rise sharply
With the increase in Smartphone usage as the access mechanism to the internet,