Symfony is a well-designed PHP framework that is growing quickly and we want to spread the word! You can think of it as PHP on Rails, and we have been having a lot of success with it here at SolutionSet on numerous types of web application development projects. The talented team of core symfony developers at Sensio Labs is constantly working on improvements, such as version 2.0 which is planned for release in November. By basing your web project on symfony, you can rest assured that it will be logically organized and perform well under high traffic load.
Releases & stable version-
symfony 1.2 The stable release
This stable version is the right choice if you start a new project today. Released in November 2008, this release has many new features and is the best choice if you want more flexibility. This version is maintained for 1 year, which means you will have support and bug fixes until November 2009.

Features:

Feature Rich – Has all the features one expects from a RAD framework – MVC design pattern, ORM tools, scaffolding, caching, authentication, internalization and localization.

Actively Developed – The team not only works on the framework, it also incorporates suggestions/enhancements from community members

ExtensivePlugin Repository – It has 647 plugins from 283 contributors

Amazing Documentation – Documentation makes ALL the difference when you have too much ofchoice.In addition to the complete API reference, you have “The Book” which is a complete reference to learn Symfony step by step. Then there are the real world examples – Jobeet.com tutorial which guides you in making a complete working website in 24 days (1 hour a day). Then, you have the customary “Create a blog in 1 hour” tutorial, and another one that makes the admin interface. Flexible –For ORM, you have doctrine and propel. For javascript you can use prototype(inbuilt), jQuery or Mootools. Supports XCache, eAccelerator, APC , Memcached for caching. Automatic Admin Generation – Borrowed from Rails, this module makes it easier to generate an optimized and fully functionalCRUD interface for your applications. Extensive developer tools – Symfony supports three deployment environments, along with very good developer tools that lets you configure, debug and monitor your application performance from the web page itself. Integrated Testing Framework – The “Lime” toolkit allows for unit and functional tests to be written and executed with minimal trouble.

Symfony with Model View Controller:

Symfony is a full-stack framework, a library of cohesive classes written in PHP.

It provides an architecture, components and tools for developers to build complex web applicationsfaster. Choosing symfony allows you to release your applications earlier, host and scale them without problem, and maintain them over time with no surprise.
Symfony features Controller, Model, and View classes, and also features some additional classes and objects that make development in MVC a little quicker and more enjoyable. Components, Behaviors, and Helpers are classes that provide extensibility and reusability to quickly add functionality to the base MVC classes in web applications.

Conclusion:

If what you need is a reliable, documented, full-featured, well supported, largely adopted, well coded, free and extensible framework, then go for symfony. Cost is the key factor. And the cost of development, hosting and maintenance of an application with symfony is less than what it is for other solutions.