^ There was only one mission where I found the stealth path to be hard to discover... and that was in like sequence 6 or 7. I haven't had any other problems.
And I actually think the combat is even easier than in the previous games. Basically you can attack until you see one of the guys attacking you (they'll have an inverse triangle over their head)... in which case press the block button (circle on PS3). If they're one of the more "badass" enemies (like grenadiers) use the block first and then the counter (X on PS3).