It's a fitting progression for Pocket, which began life in 2007 as an extension for Firefox called Read it Later. Since then, the service has added a wide variety of features and expanded to other platforms, but its core functionality has remained the same: users feed it some piece of media from the web that they'd like to save for later, and the service will hold on to it. With the new integration, users can log into Pocket using an existing account they have with the service, or sign in with their Firefox account.
It's not clear why Mozilla chose to do away with its home-grown solution for saving articles. Directly integrating Pocket means that the browser maker can rely on that company to build new functionality and focus its efforts on other areas of Firefox's development, which could be helpful. There's a clear benefit for Pocket, though: the service will likely get new users thanks to the Firefox integration.
Firefox also gained a new distraction-free Reading View that will show users an article without extraneous elements around it. It's designed to make reading easier.
Distraction-free reading views aren't anything new in the browser market, especially as of late. Apple added one to its Safari browser in 2013, and Microsoft's Internet Explorer 11 also carries the feature. However, the popularity of such features could be a sore spot for advertisers, since display ads are among the web page elements that often get stripped away.
Mozilla also added screen sharing to Firefox Hello, its WebRTC-based video chat service. The move brings the service closer in line with its competitors in the video chat space like Skype and Google Hangouts.