There can be many ways to answer this question.
Historically, one of the major negatives about China's location (for the Han Chinese, at least) was its proximity to Mongolia. Because China was so close to Mongolia, it was subjugated by the Mongols for long periods of its history.
In modern times, China's location in East Asia is a positive for it. A major reason for this is that China has a long coast that it can use for trade. China has become strong by trading, particularly with the United States. China's location, with its long coast, makes this convenient. China also (at least nowadays) lacks any major regional rivals for political and military dominance. This is a positive about its location.