I have beaten MGS4 multiple times, I have beaten it on Extreme, I have even made Big Boss rank! There is no doubt that compared to the previous games, MGS4 has less emphasis on stealth and more emphasis on gunplay. Can you sneak around? Sure. Is it as good, or even as demanding and necessary, as the previous games? No. Acts 1/2 are nice, they do a good job of building on what MGS3 started, but they're not even 'top tier' quality segments. They were building up to something interesting, but then right after that, the game completely gives up on the idea of managing a live battlefield for a poorly executed stalking idea, and then sneaking around small robots. Act 5 had a nice stealth area but it lasted for about 5 minutes.
MGS3 just makes better use of its mechanics, and gives you more freedom and time to see them to their full potential. There's more to what I mean by choosing how to play than 'guns blazing' versus 'stealth.' You constantly have something new put in front of you, with multiple ways for you to approach it. There are multiple ways to beat each boss, you can throw snakes at guards to take them out, CQC can get you through almost the entire game on its own, poisoning The Fear and shooting him with the fatal weapon will decrease his stamina bar. It's crazy to me that some people get stuck on 'menus.' You don't even need camo to get through the game with stealth! There's some real depth to MGS3's gameplay that most people don't actually put to use, mostly because a lot of people here aren't fond the gameplay side of the game, and are more focused on the narrative. MGS2 also has some deep gameplay that mostly gets brought out through the VR Missions. MGS3 is just fun to play, thought, and that's the important part.
--
"When I was a young man, I had liberty, but I did not see it. I had time, but I did not know it."