You're getting the folks behind Call of Duty and the folks behind Halo and putting all of that collective shine into a new original franchise that's still a first person shooter with strong sci-fi themes. That's got to be as sure a bet as you can make in games these days.
Destiny builds on a very simple and strong premise: you're a hero tasked with defending the last safe haven on earth. Why it's the last safe haven on the planet seems like a story fit for a brief backstory or even a full prequel at some point in the future. For Destiny we're promised travel to planets of our local solar system so Mars and Venus are mentioned by name. More importantly we're promised customization and character development around weapons, "powers" and armor. Something along the lines of what we saw in the Mass Effect and Bioshock series, a combination of mental/supernatural powers lined up next to conventional first person shooter gear sounds like a recipe for success. Combining shooting with powers means you have even more things to do that require quick reactions. Grenades, bullets, laser blasts and fireball/lightning/mental bolts would make for one powerful demonstration of a super powered hero.
It's also promising that a singular character can develop these enhancements over various game types and then deploy them across those same game types. Story mode to get familiar with your character, competitive multiplayer to get those skills razor sharp and what appears to be a co-operative team up "posse" component seem like a good way to spread things around. If this is in fact what Destiny is going to offer us and we get the precision gameplay mechanics of a the modern Call of Duty games along with the creativity and storytelling of Halo, then we're all in for a treat. Now if we can just find out what video game systems this thing will be on. I'm betting against the Playstation 3 and the Xbox 360 just so you know. Wii U, I ain't looking at you either.