So here are some thoughts
1. New Nostalgia. I love the return to the aesthetic, sets, and costumes from A New Hope. What makes this so interesting is that like The Force Awakens, this is a return to the original but in a different way. Episode VII was an homage to the characters, themes, and plot of the first Star Wars. This is returning to the world of that first movie, but it comes at it from a seemingly icier point of view. I am fascinated by this.
2. WWII Movie. Watching this I could not help remembering some of the great movies about World War II that I watched when I was younger like The Dirty Dozen or Operation: Crossbow. While the larger war was happening, these films focused on a group of heroes and antiheroes who had to accept inglorious missions to assure that the "big heroes" could succeed. I also find this idea intriguing.
3. Unique. While there are a lot of familiar sights in this teaser, it all feels so new and unlike anything in the Star Wars cinematic universe. I was a huge fan of the old Extended Universe, particularly because you could explore often overlooked corners of this movie cosmos. I see that potential here.