I'm tempted to put a mild spoiler warning on this one, as it reveals some of the central themes of Fallout 4, which you might prefer to discover for yourself as you wander the wasteland. It's hard to glean too many specifics, though, and if you're itching to see a Deathclaw minigunned in the face from several angles in slow motion, then the launch trailer does the business. Likewise, if you haven't seen anything that grabbed you about the game before now, this might ignite an interest.
It also has a lovely dog.
Fallout 4 is out next Tuesday, and there's been plenty of chatter around the last big RPG release in a year of great RPGs. The companion app is now live. There's an unofficial character planner if you want to theorycraft your starting toon. Bethesda also talked about the various improvements that have been made to Fallout 4's engine in the interim.