Once you've got something you like, you can send it to Illustrator, Photoshop or InDesign, where it automatically launches the selected application and pops open the file as a native document, with layers preserved and with elements translated to the appropriate object types. If you want, you can also duplicate it to iterate the design.
Despite its simplicity, it's pretty powerful and useful, especially for a first-generation product. It operates fluidly enough that it doesn't get in the way of the creative process. The files open in the desktop applications in real working form.
There are some drawbacks, though. It's frustrating that the libraries are unidirectional -- create on the desktop and use on mobile -- since some of the content is created on the tablet . There's no way to simply export it to an AI, PSD or IND file and save it in your cloud storage -- it either has to go straight to the application or be saved as a bitmap in your Photos.
It also it offers only the most basic features for Web design -- bewilderingly, Adobe offers zero mobile apps for that -- forcing you to use Photoshop or Illustrator as a design intermediary. And there's no support yet for video assets. I also wish it had a grid view to compare iterations and the ability to duplicate individual elements of a Comp, like Adonit Forge does.
Of course, there are a few version 1 glitches.
Despite Adobe's trend toward unifying its desktop and mobile apps with Clouds -- notably Creative Cloud and-- Adobe's mobile creative apps have always seemed somewhat fragmented to me.
There are the vastly scaled-down versions of pieces of its desktop applications, Illustrator Draw, and Illustrator Line and Adobe Photoshop Sketch (formerly); ; ; and . Then there are the useful but one-trick apps like Adobe Brush CC (for creating custom brushes from images and graphics) and Adobe Shape CC (which autotraces images), and Adobe Color CC (for generating color palettes) -- all designed to feed into other CC products.
Comp CC seems like the first app to be a hub for some of those spokes, the first stab at a cohesive conduit between mobile and desktop design. And hopefully it will get more useful as Adobe adds asset input and expanded output support for more apps and applications.