I agree with the comments on the girl. She looks great, but she doesn't add to the product or show why the M8 is the best thing of its kind. I'd look at the Apple ads for great examples of showing maybe 1 or 2 really great features of the product (even if there are a dozen great features), so people get it really quickly (so no long paragraphs of prose). The M8 is going to succeed on its own merits, and it has a lot of them, so why not clearly showcase 1 of them in the ad?
One idea might be its unique mix size and portability, and its ability to drive the biggest, toughest headphones. Maybe show some kind of visual contradiction of how tiny it is (with a coin or an iPhone), and a pair of giant orthos next to it, all done in a very clean, simple, graphic way (eg. Apple's white backgrounds with a gorgeous photo of the product). You could extend this to the breadth of its connectivity and its versatility of being a desktop and portable amp in 2 other separate ads. I'm thinking of that it's a product that manages to do the impossible: mix big and small, power and long-life, etc.
If this is going to be aimed at the Apple crowd, then doing an ad campaign that is similar in production values would be a natural way to appeal to those people.