Few suggestions for improvement:

-Account Balances doesn't show amount for "Held on orders" (at least regarding BTC). I got few orders, but it is showing 0. Also, add checkbox "hide zero balances".
-When going to specific market, show also full name of the coin, not just a symbol.
-Maybe add a link to bitcointalk ANN thread for that coin. This way, we can learn more about the coin in case we are not familiar with it.
-When making an order, the system does not take fee into account, so the "Net Total" might get bigger than our balance and then we need to lower the amount manually ourselves.

And yeah, solve all those withdrawal complaints, otherwise people will not even bother to try the exchange.