I have just started to play with the latest version of CakePHP and I got admit, it is amazing better. Compared to the old CakePHP 1.3 it is a thousand times better and it is on a point where I would seriously consider it to be a better candidate for a web application over Zend Framework.
- 30% faster
- Compatibility with old versions of CakePHP (requires migration: http://book.cakephp.org/2.0/en/appendices/2-0-migration-guide.html)
- A much cleaner and organized directory structure
My personal favorites:
- getCrumbList from the HTML helper
- getPostLink from the Form helper
- The router now supports full urls
As a rule of thumb if you are on CakePHP v.1.3 migrating it will gain right out of the box full compatibility and some performance improvement. If you just starting on a new project with CakePHP v.2.x you will right out of the box 30% more over performance, better installation and a much better structured project.
You can get more info at: http://book.cakephp.org/2.0/en/appendices/new-features-in-cakephp-2-0.html