I also always forget that the original U.S. release on PS2 (the only version of the game which I own) has the Japanese hard mode as the default/normal difficulty. All of the later U.S. releases of the game revert back to the Japanese difficulty settings and also added checkpoints.
DMC3 is a difficult game. But its almost always due to good design and synergy between levels and enemy placement. I have long maintained that people who like Souls games and want something faster, should play DMC3.