My only concern is about how they will make money. They have an Enterprise version with more interesting features but haven't seen any pricing info.
Instead, they get developers to bundle this SDK into their apps, which subsequently reports back to Twitter, enabling Twitter to track users across the app ecosystem.
I think you're correct to be concerned about how they make money, because the answer is unfortunately by spying on your users.
[1] http://www.crashlytics.com/blog/crashlytics-is-joining-force... [2] http://www.crashlytics.com/blog/crashlytics-enterprise-is-no...