I don't have any big argument against ZF -- on the contrary ; of course, I have not used all the components yet (not sure anybody has), but I've never seen anything that looked "bad" when going through the sources.
When beginning a new project, I would generally go with Zend Framework myself, actually, if I'm the one who has to choose...
There's at least one argument I would like to add to your list :
- Zend Framework can integrate with other components : you talked of using components of ZF in your application, but didn't talk about the opposite.
- A great example is Doctrine (the default ORM of Symfony), which can be used with ZF quite easily -- and is much better than
Zend_Db, in my opinion !
Besides that, I have to say that I agree with everyone of your points.
About the encapsulating ZF classes into your own classes : yes, you could do that (I sometimes do), but I wouldn't recommend doing it for everything : in most cases, it will probably not be necessary.
About the future :
- Zend Framework is released under a BSD licence -- which means what exists cannot be closed-sourced.
- Closing it would mean its end, anyway -- would be a stupid move, in the context of the PHP community
- Work on ZF 2.0 is just starting (With PHP 5.3 as a requirement, btw)
- Maybe, depending on your schedule for your application, it could be interesting ?
- At least if you don't need to start developping before at least a couple of month...
