Eclipse 4.x allow to run Eclipse RCP applications and Eclipse plug-ins which are created based on Eclipse 3.x.
This is valuable as it allows you to reuse your existing code base and evaluate advantages as the live model and CSS based styling. Unfortunately concepts like dependency for views do not work with the compatibility layer.
To run your Eclipse 3.x RCP application on e4 you only have to add a few plug-ins to your product.
After this change you should be able to start your existing application based on e4.
Quick access should not be hard-coded
[Compatibility] All views now have view menus
Compatibility Layer – Getting services via getViewSite().getServices()
Compatibility Layer – Using @Inject in plugin.xml based contribution
I hope this help. I also updated my Eclipse 4.2 Tutorial.