My Feedback

1.Design
On the top right corner on that Fin exchange Payment Methods menu ,the hover effect is not much noticed due to color similarities.Create some nice hover effect on that menu.
I love that buy bitcoin anywhere in the world option with circle image of country flags.Very creative and simple.Though so many circles makes it a look a little shady but simplifies the work of its fine.

Addons
Since you've so many countries listed ,why not show them the price of bitcoins in their own currencies ? Helps a lot for a fiat trader.For ex : An Indian would like to know the price of bitcoins in rupees rather than in dollars before buying/selling.
Might as well want to add more links of your social networks along with twitter.
Could't see terms and conditions or legal docs anywhere ?

Usability
Website is quick between navigation of links.Easy to use and fast as for now.Its modern and responsive.

My Btc : 1DPLNHcsmybXfi6CtHnj6xaYNTnKw8DfDp