Honestly biggest issue is utilizing her full potential so that she is a good heal pick vs other less skill based support hero's but if you can aim well and in a pinch with the sleep dart, she is awesome and her kit is so useful in some many ways. Positioning is a big one along with ult usage and being able to have awareness for backline dives and dealing with harressers like tracer. And to beat a dead horse again aiming aiming aiming is key