First let’s take a look at what HTML5 actually is and what it is used for. HTML is a markup language used to design and layout web pages. HTML5 is a new version of that language that has more tags and hence more design options.
Most people can agree more design options is a good thing. The controversy comes in mostly because certain companies like Apple are acting as if HTML5 is a standard when the reality is no browser fully supports it yet.
Essentially that means that for people using certain elements of it they will look nothing like they intended to most of the people who view the pages. So while HTML5 and its applications are definitely going to offer us some much cooler websites it is just not practical yet to use for your web designs.