The user interface, it's very simple to use. I can see all my orders at once without having to scroll through different windows or tabs, which makes me feel more comfortable with this program than others that require scrolling between multiple screens/windows when tracking your open positions. Sometimes if you have many items active (orders) the screen goes blank - but then reloads after about 5 seconds! Not sure what causes these issues? Other times there will be an error message saying "Error loading page" - sometimes refreshing fixes those errors too! So far so good though - haven't had any major glitches yet. Tracking portfolio balances has been great since we switched over from other programs years ago. We've also used their risk management tools extensively. And they're constantly adding new features & functionality every year! Nothing really- just minor problems here and.