The most painful thing about the years I spent working with PHP was having not even understood that web development frameworks existed. The little slice of the development world I existed in had absolutely no exposure to the concept... after switching to Python and only then discovering the concept, most of those PHP memories, in addition to being painful, became simultaneously embarrassing.
The "cool kids" in PHP are using Laravel 4. It's a well made framework. I'm doing a REST API in it at work and the lack of mind share and docs is probably the worst part about it (it's still in beta to be fair). Most of the time I ended up reading the framework code.
PHP leaves a lot to be desired though. It boggles my mind how developers who love what they do have the patience to stick with it. Example: Feature request for the unless control structure: https://bugs.php.net/bug.php?id=40296
I've seen a few people doing it. The API is quite stable since the end of last year or so I've heard. I didn't start using it until recently and I haven't encountered any bugs and whenever I gear up to do a pull request someone else has already done it.
We used Symfony 2 on projects previously. I find that it makes simple things hard to do and it is too verbose.
Laravel 4 uses many of the Symfony 2 components but makes nice facades that you can call as static methods so you never have to worry about namespace importing and it makes things a lot less verbose and easy to use.
I don't use frameworks with PHP. I build as I go, but it's always purpose-built.
I confess that I don't get the point of PHP frameworks: PHP is a framework; I've never needed to do more than tweak it a little to fit my personal style. For example, I have a "DBI" class file that's all of 133 lines (including tags & comments) that's a light wrapper around PDO, with some error logging & management and an easy iterator over result sets. It does everything I need for databases; I genuinely can't imagine needing anything more complex.
My html library is a little bigger -- 1200ish lines currently -- but that's largely because I implemented bits of jQuery into PHP ...
If it's a project you never expect anyone else to pick up then that's probably fine... but frameworks make extending, maintaining and updating projects better by keeping code organized and concerns separated, assuming multiple developers will be working with it over a long period of time.
Like mixing jquery (or any js) into PHP... perfectly valid and probably close to what it was actually meant to do, but with a framework (on top of PHP) you might have an asset loader to manage scripts and dependencies or put the script tags into view templates to keep the markup separate from the logic. In a few years if someone has to come in and maintain your code, they might be familiar with it in the context of a framework, versus having to parse everything mixed in together. Something like changing the ORM or changing the template handler becomes much easier because the framework provides that extra level of abstraction.
They also attempt to create organized and universal solutions for general use-cases, so that with minimal effort using the same framework and tools you could make any number of CRUD apps. For a lot of people it's worth the complexity to not have to deal with the overhead of picking and installing libraries or writing an ORM of their own, probably very similar to the "convention over configuration" idiom in RoR. Sometimes the price you pay for this is configurability and speed.
