0.5.x

checkout_controller is obsolete now that Spree has been refactored to use REST.
after_notify and after_success hooks are gone. See the README for how to implement them as hooks in the "fat" order model.

0.6.x

Significant database changes, do not run migrations until you have backed up your payment data.
Migrations will not port over your old payments, its suggested you write your own migration to do this in order to preserve legacy payments.