I've written a bit about playing games on Easy, and open-world games seem to be the most palpable for ratcheting things down, since the fun of the game is usually in the exploration and story-telling, not so much the dodging of bullets. "Red Faction: Guerrilla" and "Prototype," for example, were two games that I found more enjoyable on easier settings. It's too early to tell whether "The Saboteur" will be included in that crowd, but Tom French, the game's lead designer at Pandemic, definitely has that option for people:
"Difficulty settings are always tough. For our game, especially, where we have a lot of story focus, but there's also a lot of gameplay there, we wanted to make it so that anyone could sit down and play through the story. Difficulty for us is more about how much damage you do, things like that. We balance the game on the Hardcore mode [the hardest mode in 'Saboteur']. If we can play through it on Hardcore then that's a good balance for us and we just tune it down."
We wanted the player to play through the story, meet all these characters, have the chance to experience it. I can have my wife play it on easy and she gets away with it and still has fun."
I'll definitely start the game on Normal and make a judgment call from there. The difficulty settings will have achievements associated with them, so there's definitely an incentive to give yourself a challenge, but it's always a trade-off between meaningless reward and fun.