I used it for a couple of years (2009 - 2010) after getting frustrated with Zend Framework's Java-envy and enjoyed it; it was the last straw that pushed me over to Ruby and Rails, though, given Yii's attempt at bizarro-Rails with CActiveRecord, and the problems with getting testing working properly.

I really wish they would stop using statics so much, though (eg. CHtml::activeTextField()); it's really inflexible, particularly when statics call other private statics with self::... making subclassing really tough.