MGS's mechanics are unique, and something you have to learn before they start clicking. That's the reason, I think, so many people don't like MGS's gameplay. It's definitely not standardized like other games. It depends on what you didn't like about MGS4's mechanics, though. I think PW is smoother all aroun, but it might have some issues that trip you up.
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"When I was a young man, I had liberty, but I did not see it. I had time, but I did not know it."