There will be a third game, which we've been calling DD2. There should be an official announcement about it "very very soon".
Did you make it out of act 1 playing BD? Near the end of act 1 the game starts to open up a bit, with more quests and freedom of movement. The next couple acts are primarily outdoors, with a lot of freedom. There are extra monsters to kill in the battlefields, and the hardcore difficulty level doubles up on some types of monsters (once you switch to hardcore, though, you can not lower the difficulty).
Other than having 2 characters, BD's combat mechanics are fairly similar to DD. Most of the time I had both characters selected (2 warriors or warrior/archer), and directed them to attack as one.
A fair number of people prefered DD to BD (to various extents), so I assume that had an influence on DD2's design.
Welcome to the forum.
