In my opinion, new "content" is about story lines and game-play. Mostly about story line. And there hasn't been a new one in a while...
The Island redesigns were more about "interface" to me than they were about content. By that I mean, they weren't "playable". They certainly added to the playability but it ultimately had no change on the way the game is played.
I loved the cave redesigns...at first. Now it feel more like fighting in a crowded hallway...I miss the old Becket's Quarry. A lot.
GM events? Ghosts? Not even close to "content" in my opinion. They tend to happen on busy servers and I stay away from busy servers. Especially Abassa. Until Disney sends me a new video card

I will continue to stay away.
The Invasions are pretty cool but really have nothing to do with furthering a storyline. A playable storyline. Don't get me wrong. The invasions are major league fun but are, for the most part, not all that different from crewing up and going on a Tormenta raiding party.
Content to me is a playable storyline. Everything else is window dressing at best and smoke and mirrors at the worst.
BUT! And this is an important "BUT"!! I think that all of this new interface and additions and invasions and all of it are an important part of setting up the new and ever nearing Story Line. I just hope they hurry because, as I have said before, Star Trek Online comes out in February.
Semper Fidelis Pirates