This post makes me itch a bit, because it’s not correct. Now, how to put this without sounding positive…
It’s the Batman combat system, sans assault rifles (as Helio points out). It’s not a button-mashing exercise. Button mashing will get you killed in any game using Batman combat, unless it’s only a couple of mooks. Which is usually not the case with Shadow of Mordor, 10+ enemies quickly becomes the norm, and more is fairly common.
Rather, it’s about timing, combined with pushing the joystick to aim your attacks. While it feels frantic, the reality is the game strongly encourages you to act (strike or dodge) just as you’re finishing an attack. There’s a temptation to mash the attack button, but if you do that you commit to attacks when you should be countering or dodging. You will get hit and lose your combo meter.
It’s still very, very repetitive. While you have a fair number of possible attacks, in practice I almost always vaulted over enemies until I got the to crowd edge, did one or at most two attacks, and then did it again. Repeat until the combo meter gets high enough, and use a finisher to actually kill a mook, or badly hurt a captain. This handles everyone except the targets that are immune to vaulting, which aren’t common, and the captains that are immune to combat.
The actual Batman games rewarded you for using the other moves, like cape-stun. Every time you did so, your variant count would go up. Having a big variant count awarded XP. Shadow of Mordor doesn’t do that, so there’s rarely much incentive to vary your combat style.
Sneak-to-kill orc captains is usually a bad plan, since so many of them are immune to stealth attacks or ranged attacks or both. It’s not just “the off chance,” it’s the norm that he’s immune unless it’s very early in the game. There are also a handful in the late game that are completely immune to normal combat attacks - those you usually have to scare in some way. Once scared by a phobia, an orc loses all his immunities, and you can go with the standard tactics.
To finish on something negative - the final boss fight is a QTE fest. You don’t use the regular combat system at all, it’s just pressing buttons in response to screen prompts. It’s a huge letdown after the big battles that precede it.