It's not much harder. The only problem I had with it was the repetition, because I played through it 3 times in a row within the course of about a week. The best strategy I think was listed before: You have to trigger the enemies to run out and start shooting at you, and once you do that, run back (keep rolling to dodge bullets) and get behind a wall - one that is as tall as you, like a column, not a little waist-high wall - and don't press O. When you AIM, from your perspective, you can see the enemies but they can't see you. Make sure to conserve your bullets, blindfire with grenades, and always reload. Good luck.
I started playing on Crushing a few hours ago. The first 3 chapters barely have any shooting to do, and Chapter 4 was a do-able challenge. Now I'm on Chapter 5 right after all of the platforming at the beginning - haven't tried getting past where I am though, I just decided to go on the computer instead :D