Wait for Destiny 2 Annual Pass Reviews
Along with waiting for more information about the Destiny 2 Forsaken Annual Pass, you may want to wait to see what the reviews are.
It's not a good idea to wait until the reviews are out for all three episodes, since it will be too late to fully take advantage of these, but if you wait until a few days after the Black Armory release date you will be able to read the initial reviews.
We're starting to see Black Armory reviews arrive this week, and you can use these to decide if you want to buy. You may want to read these and wait another week or so to decide.
Wait to see what critics and other gamers think about the Forsaken Annual Pass to see if it's worth adding to your time in Destiny 2.