Let's dispell this fiction that C3's pricing is somehow unaffordable for commercial developers - C3 costs the same as Apple's developer license for God's sake.
The biggest selling point for me is the build server - to get a comporable ease of use service (i.e Cocoon) you'd have to pay $86 at least - for $13 more you get the build service and the entire game engine with C3! And that's not even the best bit...
No splash screens.
If you want to make an iOS game without a splash screen with Cocoon, get ready to pay $500 (per game) on top of the monthly service fee. With C3, no splash screen.
Saving $500 up front justifies literally 5 years of C3 subscription for me. Can you guys remember how far C2 got in 5 years? That was Ashley working alone - the subscription model allows for Scirra to scale their developer resources atleast threefold; I cannot wait to see what happens next.