[eluser]wiredesignz[/eluser]
Yii has many more features than CodeIgniter. Role based access control and User authentication and Ajax support to mention a few. Yii does force you to follow many of it's programming conventions while still allowing you to use some configuration similar to CI.
I have used both frameworks and I would recommend Yii to anyone wanting a PHP5 only framework. Your knowledge of using CodeIgniter will be a good starting point. But I don't recommend Yii for absolute beginners. (I'm sure they would disagree).
As far as support goes the Yii forums are well frequented by the developers and they provide great support but the CI forums to me are just far more entertaining.
We all know CI's documentation is second to none but the Yii documentation is still quite solid for all of the basic components and I'm sure it will improve as time goes on.
Quite simply the sheer volume of information available to beginners is CodeIgniters greatest asset.
