Really easy to set up a few click through interfaces and share it. Free plan is generous if you don't need commenting. It works best with straight forward interaction flows. It supports both desktop and mobile just as well. Sharing is done with a private URL that loads perfectly on desktop and mobile.

The Simplicity. It is the most simple to use app and user friendly with extreme power. There are rarely anything which I would not like in this application, from the UI to almost every feature I just love it. I started using this software recently but it really helps you, specially for big projects. Personally I prefer using marvel instead of github while working on web development application. And the image editing tool integrated with the application also comes in handy most of the time, when you want to tweak some minor changes in your image. The ability to downlad the prototype in different forms is again my favorite feature.

I use Marvel app mainly to share my wireframe and static prototypes with my team. It has a super simple and intuitive UI, the learning curve is gentle. The "hotspot" system makes easy to connect the screens of your prototype and probably it works smoother than its competitor Invision app. Also the "embed" feature allows to share your prototype anywhere, even on Twitter.