There are some spoilers, but they aren't going to ruin the game...
This game is going to be freaking amazing.
They've made the space travel system much more in depth. You burn fuel to travel to planets and you have to survey and analyze planets before finding a place to land and explore. They're also a lot more interesting apparently.
The combat looks much better.
And as always with Bioware games, there is real variation to the endings and the plot depending on how you play.
This is easily my most anticipated upcoming game.