Magazine UX is probably the Flipboard engine, modified to launch a couple of Samsung Apps.
At least it will look and behave Flipboard-like, which can get annoying soon.
When it was announced M-UX was a replacement UI, was set as the default home page, came with three pages of M-UX content installed out-of-the-box, and had a ton of live widgets and the ability to add a tile (shortcut) to launch any installed app.
From the Verge in January...
The new tablets feature Samsung's new home screen layout called Magazine UX. The layout offers tiles of apps and information that users can customize and configure. Three preset pages are offered by default, though users can customize up to five pages with apps and news widgets. The whole system feels very similar to the LiveTile system in Windows 8.1 and is a bit more approachable for new users than the typical home screen. Ironically, the power users that Samsung is targeting with the Pro tablets will likely find the Magazine UX too constricting and limiting.
Since then it's been renamed from "M-UX" to "Content Home," reduced to a single home page that's no longer the default (standard TW is), half the widgets shown at MWC are gone, and so are the tile app shortcuts. My guess is that it's been neutered as part of the cooperation agreement signed between Google and Samsung. Samsung Hub which was a content competitor to Google Play is also now gone on the Pro's.
To your point, what's left pretty much is a more flexible version of My Magazine that allows you to choose and re-arrange what news and social content is displayed on the page. Based on what it's ended up being I won't be upset if our update doesn't include it.