I have zero patience for MGS, precisely because of the stealth elements. I don't know if it's because of how dumb the AI is, the finicky controls, or just my general distaste for sneaking around as opposed to just killing everything in sight, but I tried the original about six times when it came out and just couldn't deal with how stupid it felt. I had a similar experience with the GameCube remake.

The way stealth works in Assassin's Creed sits much better with me. Probably because there's more of a mixture of elements--very rarely is there not more than one way to do things, and there's always a plethora of ways to get out of trouble if you can think quickly under pressure. The AI is also way more realistic and less video-gamey, if that makes any sense.