The main thing about BD is that shooting those robots was fun, 'cause the fell apart, and lost functionalities depending on where you shot them.
Kind of a simplified version of RE2 remake's zombies.
Plus the visual design and the world were kind interesting, and had some cool set pieces.
It didn't reinvent the wheel or anything, it was a cover shooter, but it was very satisfying to play, more than most in the genre.
Too bad the PC port is ass, and just a pain in the ass to run properly.