The App using public have become accustom to using highly polished products which have had multi-million dollar development budgets (thanks Google, Facebook & Twitter!) and therefore, users expect a certain level of quality when using mobile applications. 
This high expectation of quality makes it rather difficult for individuals/organizations who are looking to develop their own application, especially if they’re working on a tight budget with little or no in-house coding resources.
Apps heavily rely on blend of ‘Design’, ‘User Experience’ & ‘Seamless Functionality’ to capture and hold a user’s attention, as they need to continually encourage a user to open and interact with the application.
The only exception to this rule, is an application which performs a ‘modern-day necessity’ such as a mobile banking app, which can get away with offering a slightly ugly or clunky experience.
In my opinion, it is very important to have a decent budget when developing an App. Ensuring each of the three afformentioned areas of development are allocated sufficient budget to ensure you’re going to deliver a solution which people are going to want to use more than just once and keep it on their phone/tablet is crucial to the success of your mobile application.