Just a simple request from a fellow coder who has otherwise had a wonderful time building applications with this plugin:
Please try not to change the storage format for your metadata suddenly. Or when you do, a) provide a way for developers to alter it and b) let us know in the changelogs.
Specifically, the change for Relationship fields in v3.3.3 from comma-separated to PHP-serialized has just broken some code. I was using a relationship field with a single value and was querying against the post ID directly.
I understand that most of the users/customers of this plugin never touch a line of code, or use your API calls as provided. I am not in either group. :)
Besides that, thanks for creating a great plugin that is both useful and well-coded with other developers like myself in mind.