Easy to use, great customer service, fantastic execution of trades - I have no complaints! The interface could be improved by adding more features (e.g., margin calls).
A better charting tool would also help with visualisation of price movements over time. However, this should not distract from CF's core strengths which are its ease of use & low spreads for traders who trade less frequently than once per day. We can execute our order flow efficiently without having to resort to dark pools or other non regulated venues.