China has the world’s largest installed base of connected devices - almost 25% of the world’s mobile devices. 500 million Smartphones are predicted to be active by the end of 2013, and possibly exceeding the combined European and USA smartphone user market by the end of 2015!
Although Chinese users follow the rest of the world in their interest in games, compared to American users, they tend to be more interested in news apps and are more likely to make in app purchases.
The English speaking world has traditionally been the largest market as localization is fairly painless. However, this market is becoming saturated and developers have realized the need to look elsewhere. China seems to be a good prospect despite the many barriers to entry, such as piracy, monetization difficulties, fragmentation of the distribution network and naturally cultural differences.
Developers in the smaller non-English speaking countries were forced to consider the Chinese market a while back. The decision to do so was made easier for them as they already were faced with a small local market for their apps. It was natural for them to expand into foreign markets including the English market. Localizing their apps for the Chinese market was no different than doing so for the English market.