Hi!
We wrote up a page in our docs address this: docs.expo.io/versions/latest/introduction/why-not…
Here are the high level bullet points:
- Expo apps don’t support background code execution
- not all iOS and Android APIs are available in Expo (in particular, payments and bluetooth and real time video streaming are still in the works)
- If you need to keep your app size extremely lean, Expo may not be the best choice
- If you know that you want to use a particular push notification service
There are also reasons why you may not want to use React Native. For example, if you are doing some kind of real time fluid simulation, or having the fastest possible cold boot time is critically important.
We have plans to address all of the things listed above but it will take us a little bit of time.