I played the demo, this seems to be a very good game. But I have two very major gripes.
First, I'm running a wide screen (mac book pro, leopard, bootcamp, vista) and due to 1400x900 resolution the game looks kinda not so good as it could. I 'm pretty certain that adding a resolution is *not* that complicated, if you just scale and don't use different sprites (if you did that, I would be quite impressed).
But second: Since the order form does not allow me to use öäü (why exactly? Shouldn't html/java/whatever you are using support unicode by default?), I cannot use my credit card since my billing address includes two ü's... You could also just remove the address check (I did not exactly try, but I assume you are checking, because you explicitly state "as billing address for CC" in the text), like amazon for example.
Kind of annoying to not be able to buy a game because the company does not want my money. And yes, I have the exact same problem with steam too...