It's funny, all this talk about Diablo and what makes a RPG. BD is a step up from Diablo, but not by much. It's very like Dungeon Seige but with lesser graphics. I wouldn't say BD is a RPG, and DD only just scraped in. DD had too many scripted points were the player lost control so the the developers could progress the story (A major mistake in my mind). Also there was little in the way of branching dialogue in DD and there is little in BD as well.
Now true RPGs, well the best examples you can get in recent years are Fallout and Planescape Torment. Both offered highly detailed worlds, full modification of the PC, complex NPCs and clever dialogue branches that depended on your PC (and the player) and resulted in very different outcomes. If you never played them go find them in a second hand shop somewhere. As far as I know these are the only games where you could fight or talk your way into beating the enemies...or any number of other clever things.
Very much like Dungeon Siege? Last I play the game, I cannot mix healing potions from herbs growing around, drag items around the place, have conversations with NPCs in body, got any type of meaningful conversation tree and my NPC members are pretty much on auto-run.
