Q u o t e: I feel like the Dark Ranger is designed specifically to fill every cliche Blizzard has avoided so far with their character design.
Dual wield crossbow. Is mysterious. Is a loner. Demons killed her family, she uses Ninja moves, gadgets and Demon magic all together. She knows "the true threat of demons" according to Blizzard while the rest of the classes are "in it for personal interests". She has a British Accent. Her Eyes Glow.
It feels like there's nothing that makes her Interesting. Barbarian is a raging old man. Wizard is a teenager with too much power. Monk enjoys beating the snot out of others a little much. Witch Doctor is foreign and mystical.
Maybe conceptually that's the problem with her: she's a Demon Hunter in a world full of demon hunters. All of the other characters may have a back story explaining their origins from a different perspective, but have we ever seen that in any of the games? The games have been geared towards eliminating demons and their corruption from the face of Sanctuary and even further. Perhaps it's a flaw in the series itself that lends itself to the feeling of the Demon Hunter being lackluster. Then again the games are all dubbed Diablo, so ofcourse you have to be killing demons, but perhaps in the previous games there just wasn't enough lore to provide for her appearance. In any case the Demon Hunter just doesn't cross the threshold of "believability" for me and several others apparently.