I have some concern/suggestion.
* If this is an instant exchange, put the value that the user will get in return after putting the amount to exchange (or estimated value atleast, just put a note if ever). User should know the rate
* You don't have an address checker, am I right? I tried inputting a random letters and it proceeds.
* You need an FAQ
* Isn't 0.05 BTC too low for max amount?