I would say judging MotN by the demo doesn't really allow you to see how challenging it can become. There is some serious instances where you have to plot out each tiny movement (even when you're a leveled up badass) or boom, you're dead. The checkpoint thing just makes it so you don't feel like you're stuck in a situation that you can't fight your way out of because it's a stealth game. But anyway, I won't derail any further.
I personally liked that aspect of Hitman. The ingenious ways you could pull stuff off. Blood Money especially was THE game for plotting your movements and decisions wisely. I remember the Opera level (which was probably my favorite) where you can get a real gun that looks like the prop gun in the play, swap it out for the prop, rig explosives to the auditorium chandelier. Then, target 1, the dude in the play rehearsing, would get killed by the guy thinking he had a prop instead of a real gun. Seeing this, target 2, a guy that loves watching target 1 perform, finally comes running out of his booth and down the aisle when he realizes his friend is dead. That's when you blow the chandelier, which falls and crushes target 2. You walk away unseen, and get that sweet newspaper write up which essentially acts as if this crazy double tragedy happened at the Opera because they have no other clues.