So far, use it to production servers is not recommended, the reason is simple - errors may occur.
But do not wait for a stable release, we must begin now to its development and to create test applications!
Features of the second version:
- Requires PHP 5.4 or later version!
- You must use namespaces.
- New avtoloader classes.
- New RBAC, it has become much easier.
- Built framework for creating REST API.
- Adds new features for testing.
- Added new validators and improved others.
- ActiveRecord-added implementation for different types of databases.
- Support for nested tarnzaktsy.
- ActiveRecord converts the data to the appropriate types.
- Added batch requests.
- Query Designer supports nested queries.
- Hierarchical filters, they can now be applied to applications and modules.
- Added helper to work with URL.
- Added comfortable and beautiful debugger.
How to update Yii Yii 1 to 2 can be read here .
Documentation Yii 2.0 is here .