How can I check the usage of my iPhone app in iTunes connect?
For example, the number of times the application has been launched on the user's iPhone.
You can't see more info in iTunes connect then the number of downloads, by date and by country
To see more, you'd need a third party analytics library built into your app, but I don't know what Apple's policies are. I've heard that Flurry is a decent analytics library, but I don't use it.