HTML5 or otherwise-known-as, Web Apps, are simply that, applications that have been built using web technologies such as CSS3, JQuery and HTML that make use of a mobile devices browser rather than having any Native components. It is therefore not necessary to develop a new app for each type of operating system as it “should” work with any mobile device's browser. In reality however, every device has its own browser and it takes significant browser testing to ensure that your Web App is compatible with most devices. There is also the issue of backward compatibility meaning that even if your web app is compatible with today's browser version, it may not be so with 2 versions prior and herein lies the problem. HTML5 is also only compatible with some of the later browser versions and newer handsets and if your target market is not in that demographic, then you may want to re-think the use of these type of web-apps.

They do however offer basic hardware integration and there is definitely a space for them provided you have done the research.