iOS developer Genady Okrain writes about his experience making money (or not) developing an iMessage app. Cutting to the chase:

As you can see the iMessage App Store was very promising at the beginning but nowadays it is somehow abandoned. This led me to release the app as an iOS app with an iMessage extension, and it is much more successful than just the iMessage app.

Interesting read. Not easy to make a living as an indie app developer.

My 2 cents: Articles like this are good input for folks just getting started, trying to sort out the best direction to take.