If you're viewing this site in something older than Internet Explorer 9, firstly NO! Bad internet person! No! I will rub your nose in the keyboard to teach you you're doing it wrong. Secondly, it's probably for the best to use something more modern like Firefox, Chrome, or Opera.
HTML5 has shown some real potential for creating a more personalised website. For example, let's say your company has a promotional video they wish to share with the world. Before you would either have to go through something like YouTube, which would likely stick out like a sore thumb compared to the theme of your website, or even code your own movie player which is time consuming. With HTML5, anyone can host a video directly though their site. It makes the website prettier, your video is your video, and you don't need to be bogged down with any Flash.
The same also applies for viewing multiple images on one page.
There's some fun elements added to HTML5, which some developers think is a good opportunity to use for easing into the Flash game market.
But I ramble. Here's a quick example for you - do you see that sexy dark green navigation bar that's following you around at the top of the screen? Try readjusting the size of your browser a bit. That's right, a bit more. There we are! See how the link have disappeared? Well, fear not - just click on the button that's appeared on the right hand side. Cool, eh?