I'm not a huge fan of the way Facebook wants to be a "roach motel" on the internet: content checks in, it doesn't check out. It's a problem on the mobile app more than the desktop website, because sometimes I'll see an article I want to read, or a video I want to watch, but I can't right now. From that point of view, I'm glad they've introduced "Facebook Save", which is a glorified bookmarking feature to let you save an article for reading later, into a special feed on the Facebook site.
What bothers me is that this plays straight into their roach motel business model. See, there are plenty of other bookmarking tools out there, and plenty of services to save articles to read later. I use one of them often. It's called Pocket, and it's fantastic. This Facebook one could very easily be replaced by Pocket, if only the Facebook mobile app had a "share" function that worked with the normal Android "share" channel, instead of assuming that Facebook is the only place I would ever want to share something I found on Facebook.
This was clearly not the easier path for Zuckerberg Incorporated. Adding a whole new level of functionality to Facebook should not be the default behaviour. It's big, it's potentially buggy, and it reinvents the wheel. The only reason to behave this way is to avoid the suggestion that there's anything on the web but Facebook itself. In other words, Facebook went to a lot of trouble and expense to keep you on their site, rather than learning to share.
Mokalus of Borg
PS - I've checked for the new function but I can't find it yet.
PPS - Functions like this tend to roll out slowly.