Hey coinmarket, I have done quite a lot of trading in the last few days. Overall everything works very well, fast deposits and withdraws, fast and clean interface and easy to use.
I have had a few problems though:
Often the interface doesn't update when navigating to a market from a non-market page. E.g. I will be on the USDE/DOGE market but the interface will say USDE and BTC.
When clicking the auto-fill max button when buying or selling there is often a rounding error which means I have to change the last digit to submit the order. Very rarely my order will actually be submitted and the interface will say there is an error, this may also be caused by different rounding on the client and server side. I think I may have encountered a rounding error on withdrawal once as well.
I know it's not a big deal and you are probably not very concerned about the design right now, but I feel that the one thing letting the site down is the tables. If you could update the table design it would make the whole site look a lot better. This article has some nice ideas for styling tables:
http://coding.smashingmagazine.com/2008/08/13/top-10-css-table-designs/