There have been lots of changes to improve its use from both a development perspective and it’s user experience.
Some modules and components such as old payment methods and compilers have been removed, these will be replaced with new updated functionality and available as community extensions. A few functional changes have been made to make it easier for us as developers to design and develop themes within Magento 2; the theme config is now in just one field and email templates are controlled per module, making it easier for us to make changes.
A complete overhaul of the file structure will result in increased modularity of code for easier and more efficient development of magento extensions, root items have been relocated into public/non public files for greater security and there is a unified entry point through one bootstrap making it easier to put the site into maintenance mode.
Naming conventions have been updated in Magento 2 to use only fully qualififed names, aliasing has been completely removed reducing the config xml size by 10% – 20% improving overall site performance. Rewrites are also much simpler now and all xml will be valid.
Code testibility will be improved by utilising dependency injection and zend framework 2 components which will enable us as web developers to irradicate potential problems alot sooner in a project’s dev stage.
Integration with other systems into Magento 2 has been improved with increased functionality coverage for the Web API through the REST API and SOAP. The performance of the Web API will be enhanced by a new granular WSDL and improved routing methods.