If you are on subscription there are lots of advantages of being on CC. You are always working on the latest software which has the latest features/updates.
Here's what's new in Dreamweaver CC.
If you are a designer and work with a lot of CSS, the CC version has a new CSS designer that allows you to work visually with the CSS properties and in combination with live view, you can see the results almost instantaneously.
If you work with responsive designs very often, the enhancements to Fluid Grid layout is new. You can use the visual tools on the Fluid Grid page to do quick operations that helps you do the layouting much faster.
We have modernized the entire application by getting rid of features that were no longer used/outdated.
We have also integrated Web fonts so you can add and use webfonts to your design from right within Dreamweaver.
With the CC update (13.1) that we did a few months ago, we have made code view improvements, added sync settings features to sync keyboard shortcuts and workspaces in addition to Application Preferences and site settings. We have added a new feature called Live highlight which will give you a visual indication of the elements on the page that are affected by a CSS selector.
The main plus point in 13.1 is the Live view. The live view will show you exactly what is rendered by most browsers today. This will help you avoid workaround trips to and from browsers.
Support for PHP 5.4 has been added.
Plus lots of bug fixes have been made.
Sales pitch that does not really tell me what I can get in CC that I can't get in CS6.
I run Adobe Creative Cloud, and it tells me when to update my apps, same as CC unless I missed something.
How is CC worse than CS6?
CC is probably only any good if you intend to persue responsive web design and DON'T want to manually get your hands dirty in the code. From what I hear CC improved its fluid grid system from that which was released in CS6. But I doubt it will keep pace with what's happening and undoubtedly will be dead in a couple of years, much like everything Dreamweaver introduces...it has a very limited shelf life.
CC dropped support for easy database integration i.e. server behaviours although it allows you to add the extention back OR some of it BUT not all of it.
I'm waiting around a few years before I decide which direction to take concerning html editing software. Do I really need Dreamweaver any longer, not really. Once you have learned html and css then you could use any old html editing software.
Use both and make the decision as to which one will benefit you most from actual use.
You can have both installed if you are a CC subscriber, you just can't run them at the same time.
Here's how you get DWCS6 if you are a CC subscriber...
I have to strongly disagree with Nithya about Live View in 13.1. It's closer to the real thing, much closer than previous versions, but still far from showing you "exactly what is rendered by most browsers". A fair bit of css3 is still ignored or rendered incorrectly in DWCC 13.1.