I've only experienced with CodeIgniter 1.7 roughly two years ago, quite okay but there were flaws such as you can have only one controller, no redirection to another controller, etc; I was also playing around with CakePHP a little bit but to be frank I was not very used to its "Ruby on Rails" approach of convention over configuration, so in the end I just gave up.
I am planning to have a new casual web application after work for myself, and this time I'd like to try something new, I've done a little research and found two candidates:
Both sound very promising but I'd also like to hear the advise from their users, hopefully this would get a decent feature comparison like the thread about CakePHP vs CodeIgniter on SO
If the debate is between Yii and DooPHP, go for Yii. Not only is DooPHP a horrible name (seriously, would you ever want to tell a business client "I used DooPHP"?), but Yii is simply solid. Thus far, the versioning has been fair. When I used Rails, I was bombarded by crazy changes every month or two and "forced" to upgrade constantly. Yii has added real value features each version, without all the hype that forces a ton of upgrading all the time. The community is solid, the performance is great, and despite a decent learning curve it's not difficult to get up and running quickly.