I love this game, it is in my personal opinion one of the greatest videogames I've ever had the honour of playing. But I've since found that I can't simply play Metal Gear Solid 4 on it's own. You see just before MGS4 was released, I played through MGS: Twin Snakes, MGS2, MGS3 and MGS: Port Ops. Playing through much of the franchise I personally think made me appreciate MGS4 a whole lot more for everything it did. It felt special and made the overall story even more enjoyable. It was almost as if I had gone on this journey with Snake so the ending of the game felt more important. 

I've only played Metal Gear Solid 4 once. It nearly made me cry. I feel like I'll never be able to play it again. It's almost like it won't do it justice.

It's weird.

Played it twice last year and now its covered in dust

I played it once, now I would just watch someone play the whole MGS saga up to 4 rather then play them myself.

I only have MGS2 for the Xbox.  I tried it, and couldn't find it even slightly interesting.  Now it just sits on the bookshelf, in good company, but doing mothing.  Hey, I tried it.

Perfectly reasonable to feel that way I guess. I mean MGS3 will always hold a special place in my heart, right next to my girlfriend and George Carlin xD But I can see what you mean, together they are all great, but as one they are a masterpiece. How a work of art should truly be, each one compliments the last, with the finale turning out a splendid show of how the series has evolved from the start.