  App stores are highly competitive markets, sometimes offering dozens of apps
for a single use case. Unexpected app changes such as a feature removal might
incite even loyal users to explore alternative apps. Sentiment analysis tools
can help monitor users' emotions expressed, e.g., in app reviews or tweets. We
found that these emotions include four recurring patterns corresponding to the
app releases. Based on these patterns and online reports about popular apps, we
derived five release lessons to assist app vendors maintain positive emotions
and gain competitive advantages.
