Game wasn't bad^, yet it was far too easy to just kill everyone. MGS 3 had this elaborate martial arts system you had to master, it even relied on how hard you pressed buttons, and in Chaos Theory you just push a button and Sam stabs a guy or knocks him out or breaks his neck.
Sam's guns were also weird and there was always that artificial feel when the game gave you "warnings"
He is still a bad ass though.
The trick is to find intersting ways to subdue/kill without using guns at all. Using guns in Splinter Cell is for sissies.

Example one time a guard was in a rec room using a treadmill because he was bored. Well there's a dozen ways to handle a situation ranging from sneaking to shooting. I sent an EMP pulse into the treadmill so it's motor seized. It threw him off balance and he cracked his head off the machine.

Getting a 100% rating on a level in hard difficulty is extremely challenging. No alarms, never detected, never seen, no fatalities in some cases, bodies never found, fast mission time etc.
I tried to get into MGS. Tried pretty much all of them. It's sort of a Arcade Stealth as opposed to Splinter cell's simulation. Or Ridge Racer versus Gran Turismo. I wasn't a big fan of the weird magic or 4th wall stuff, but the cutscenes were nice. I still prefer the Nes ones more, even the bastard child. I've always felt SC tried to emulate what made the Thief series good in the past. I'm hoping Asassin's Creed does as well.