When people complain about the Facebook app on Windows Phone "screwing up" their feed, I wonder if you've / they've ever used Facebook on iOS, Android, or the web.
Showing posts out of order, never showing certain posts, showing confusing updates when you update your feed, etc. - those are inherently in Facebook's control and manifest in the same (or very similar) ways on all platforms.
The Windows Phone facebook app is certainly missing some features, but don't think that the feed itself is screwed up for any reason that doesn't also exist on other platforms.
I agree, it's just how Facebook presents stuff on all platforms.
The new app seems pretty good to me, I am not a heavy Facebook user, but it accommodates my uses well.