Recently, I got a chance to play a portion of Destiny 2's opening mission on PC, titled Homecoming.
It's apparent from the start of the mission that Bungie is responding to the criticism it received from the lack of a real single-player story in the original Destiny. Instead of just going to some vague quest marker where I received instructions to go kill something and get some loot, or watching some cutscene I felt barely any connection to, I actually felt that the stakes were raised this time around.
If you've seen the trailer, a few scenes of which are in the opening mission, then you already know that there is an actual story to be examined in this game. The mission starts with the destruction of the good guys' home planet by the Ghaul. I was tasked with tracking down important characters, all of which were either evacuating civilians or taking down enemies.
The structure of the level was a mix of linear and more manueverable, open space where I could strategize a little more. The gunplay was intense, and my special move allowed me to slash enemies with a giant flaming sword proved to be more than helpful a couple times.
The environments were suitably chaotic, and it's clear that Bungie did their homework. I talked to a developer on the game, who said that the opening mission was something like a primer, giving players an example of what the rest of the game will be like. So expect a mixture of linear and open world when Destiny 2 launches on September 6th for consoles and October 24th for PC.