Meh, I never felt like I was in over my head. The only level I can think of that gave me real trouble in the franchise was the asylum finale in Hitman 1 or 2, and that's only because the map was confusing as hell.
47 should be a skilled killer, but one of the big challenges of the game has always been to kill your target and escape undetected. It's never really been about going in guns blazing and merc'ing everyone. You can do that, sure, but there's a reason there's a ranking system for every mission, and that the highest awarded is for being undetected. Also, just because 47 is a skilled assassin doesn't mean the game shouldn't be challenging. Sure, you should feel like a bad ass, but if you're trying to infiltrate a mansion that's packed with armed guards, it should still be challenging IMO. Otherwise, what's the point?
If anything, the shooting mechanics and stuff could use an upgrade, because they could sometimes be frustrating. But as far as stealth/planning goes, I hope they don't nerf it too much.