In my experience, the main benefit of doing the early mobile check in is that they will make your keycards earlier, so it saves ~30 second when you interact with the FDA and they don't need to create your keys. Any benefits beyond that are extremely variable. Most of the time I end up having to wait in the regular line (some properties have an "elite" check in line, which sometimes is staffed, sometimes isn't). Some properties will upgrade you ahead of time and you can see that reflected in the early check in. Others won't.

I like the basic property briefing as well if it's my first time at a property. But I find this really variable too, varying from property to property. (If they don't do it, sometimes I'll explicitly ask about at least the lounge location).

(Note that I find these differences to be property dependent, rather than brand dependent, suggesting it has to do more with local management than brand standards).