I'd never heard of Symfony before. Can someone point to some tech details about the framework? The site does a lot of explaining what a framework is, and some general philosophies - but not what this particular framework is.
In terms of functionality, it's basically for PHP what Rails is for Ruby, but unlike many other PHP frameworks, it's been designed with the platform in mind rather than trying to force Rails' concepts into PHP, as a result if which it feels "just better". This has given it an edge over competitors, which is why Symfony is remarkably popular among the more professional PHP businesses.
I think it's basically the only mature and popular surviving framework that dates from the blast of PHP frameworks that came to be when Rails got popular and PHP coders wanted that too.
isnt it so that its much easier to find a Zend plugins/libraries or Cakephp ready-made plugin/library than to find Symphony code snippets
Zend is well-written and solid, but old; it hasn't been materially upgraded for PHP5.3--which is all you should be using these days, there's no good reason not to.
Symfony2 can trivially use Zend-based components. (It does, for some tasks.) I've heard it wise-assedly called "ZF3" because of its compatibility in the past.
Popularity:
Another way to understand the level of the community commitment is to compare it with other projects. Symfony2 is currently the most popular PHP project on Github (most forked and most watched overall) and the 12th most forked project for the whole Github platform. That's just astonishing!
Standards compliance:
Symfony2 embraces standards: First, Symfony2 is willingly centered around the HTTP specification (just have a look at the built-in HTTP reverse proxy). Then, we are embracing the PHP standards: PHPUnit, namespaces, PSR-0 autoloader, ... That makes Symfony2 easily interoperable with many other great PHP libraries.
Caching:
By embracing the HTTP standard, and thanks to the ESI standard, you can make your application fly very easily. Make your application as dynamic as you need it to be, and still benefit from HTTP caching. And if you can afford the installation of a reverse proxy like Varnish, the performance of your application will just be incredible.
Saying the effort should be put into some other framework is effectively turning the case upside down.
There is already a compatibility bundle for running Zend Framework apps with Symfony2:
http://symfony2bundles.org/beberlei/WhitewashingZFMvcCompatB...
And I'm working on another bundle that allows running Midgard MVC apps:
Between Symfony2 and Silex, I'm not sure what case there is to use anything else anymore. It seems like the low and high ends are very well covered in the Sensio Labs environment, and I'm not sure how much room there is in the middle.
Doesn't matter, though. We're building compatibility bundles for both. Though Midgard MVC is already in somewhat running state.
I know that HN is somewhat ignorant of the PHP community due to the large set of idiots there and the so not cool factor, but you're taking this to the extreme. Symfony is probably one of the most decent and most widely used pieces of open source PHP out there.
(This may be a bit flippant, but seriously--there's not really a good reason to be using stuff like CakePHP, etc. in 2011.)
Symfony2, on the other hand, is very well-designed (separating entirely from Symfony 1.3 to develop Symfony2 was a great decision), incredibly flexbile, and amazingly performant. It is, no exaggeration, the best PHP system I've ever seen, open-source or otherwise; unless you're Mr. Potencier, reading its code will make you a better PHP programmer. You can actually strip it down so far as to be just a microkernel + dispatch, which is what Silex[1] is. You can also built all manner of whatever-you-want on top of it. There's no real downside to using at least part of the Symfony2 ecosystem for any PHP project.
Maybe they fixed this, but last time I used Cake, for instance, if you were overriding hooks in the Model to e.g. change the data as returned to the view/controller, you had to do this different depending on how the data was collected. So in the same hook method of the BananaPeer, you either got a single Banana, or an array of Banana objects, or an array with a key "Bananas" which had an array of Banana objects. There was no way to figure this out except with a lot of testing. There was no uniform way to implement standard features and constraints inside the model.
Cake was full of this kind of shit. It was, simply, horribly badly designed and to my impression only popular because its web site was pretty. The source code was horribly undocumented and the internal SQL query building process was a disaster.
I think that, next time someone asks me why Cake sucks, I'm just going to say "BananaPeer" over and over again.
Because bananas don't have peers.