In general I should say that Joomla 3.4 have already all new features build-in since January 20th 2015 - when developers decided to freeze add new ones. Since today you can download J! 3.4 Beta 1 and check what is inside.
Stay Tuned for New Features!
Read this page if you want to get to know of exciting new features we will be available in stable version shortly. New Joomla 3.4 focused on only four main new features and others improvements, though most average users will only be able to notice few of them. Joomla Developer Team has been working hard to ensure the product still meets market requirements: in other words, to make it perform better for your business and personal purposes.
Back-end Isis Template improvements
Some filters from top has been moved to left side, as the sidebar box. Right now you don't forget about those options and still you can hide it using [x] option.
Sidebar Filters Box in Module Manager - New in Joomla 3.4
Weblinks Component Removed from New Installs
Joomla Team decided to remove (de-coupling) components which have modest possibilities and in modern times almost nobody use them. Weblinks is a great example of this issue, and so from Joomla 3.4 com_weblinks and all associated modules and plugins has been removed from the Joomla installation package. This is a another step in making Joomla package more lighter.
Front-end Module Editing Improvements
Even in Joomla! 3.2 you might have noticed ‘edit’ icons appearing in every module when you are logged in on the front-end as a administrator; clicking them would redirect you to the module configuration page in the back-end. One of the coolest things about upcoming Joomla 3.4 is it will change this behavior to allow you to modify modules without the need to access the administrator area. Is just amazing feature (at least) and cuts user training by half as the whole front-end back-end concept no longer needs to be explained to the person managing the content. The authorized users (with default Joomla ACL) will even have access to the same options that they would during editing in the Module Manager.
Front-end module editing in Joomla 3.4
Don't forget that in Global Configuration Super Administrator can also disable mouse-over edit icons, using "Mouse-over edit icons for" option. By default this feature should work in all Joomla 3.4 templates.
NoCaptcha Build-in Plugin
In Joomla 2.5 and Joomla 3.3 there were ReCaptcha plugin (service) used to prevent spammers. And now in Joomla 3.4 you will get NoCaptcha plugin. Uses will not have to spend their precious time on annoying attempts to understand hard-to-read words, combinations of letters before sending a Contact Form. Following animation will show you main difference in appearance.
On Joomla websites using this new API, a significant number of users will be able to securely and easily verify they’re human without actually having to solve a CAPTCHA. Instead, with just a single click, they’ll confirm they are not a robot.
Continued Microdata Implementation
Microdata in Joomla was introduced with the release of 3.2, and Joomla 3.4 will go even further, continue implementing this feature in others Joomla’s core components.
Composer Integration
In the 3.3 release, Joomla Team introduced code from the Joomla! Framework into the CMS, however, the method in which it is installed into the filesystem does not align with how Composer installs code. For the 3.4 release, they integrated Composer into the CMS for managing external dependencies such as the Joomla! Framework and PHPMailer.
Joomla 3.4 Beta Download
Joomla! 3.4 Beta 1: https://github.com/joomla/joomla-cms/releases/tag/3.4.0-beta1
This is a BETA release, that should only be used on test sites.
Helix 3 & Joomla 3.4
The new JoomShaper Helix v3 is and will be fully compatible with all new Joomla 3.4. Beta/RC/Stable versions and will be available before end of this week. Also all upcoming JoomShaper Templates will get this framework inside package.