I´m use Yii 1.x in my projects, and I have same doubts about Yii 2:
Yii 2 is beta? There is a date to final version?
My project using Yii 1.x can be migrate to Yii 2?
Yii 2 is like Yii 1 to write codes or there is a significant difference? For example now I write my code using Yii 1, if I start on Yii 2 I will have to learn many differences?
Yii2 was released as a release candidate yesterday and is expected to reach GA (general avalability) in about 2 weeks, so it’s not in beta anymore but soon-to-be-stable, anyhow there is no fixed date as far as I know. Migration from yii to yii2 is not as trivial as it may seems, please refer to the documentation about upgrading here.. You can not replace the current framework with yii2 and expect everything to be running fine out of the box. In my opinion you’ll have to learn a few new concepts which seem way more intuitive so it shouldn’t be too hard