Like usual, Hideo ties in the story a little too much, but the gameplay is definitely worth it all.
Storyline: 10/10
Hideo Kojima definitely knows how to put together an amazing story that includes so many twists and turns that you might need a database to keep track of it. Luckily, there is the Metal Gear Solid Database on the PSN Store for free. Although the story tends to steal the gameplay's thunder, it does include flashbacks (triggered by tapping X) and first person view of the area through Snake's eyes (triggered by holding L1). You will see many familiar characters who end up doing things that you have never expected, and you will see someone raise from the dead.
Gameplay: 10/10
As old as Old Snake is, he can pull off more moves than ever. Utilizing CQC, guns, & stealth, he must get to Liquid Ocelot and kill him. Also, the attack button, which used to be square, is now R1 (just a heads up).
Once you have the enemy in a chokehold, a number of things can be done. You'll have to figure that our for yourself, though.
The guns look a lot better a slicker than before. You can go to Drebin, a gun launderer to buy guns and other things. You can add a lot of new things to certain guns, like laser sight, flash light, scopes, & supppresors.
Stealth is taken to a new level in this game. Instead of repeatedly pausing the game to change camo, you now have the OctoCamo. Just press up to a wall or stay prone for a second or two and the OctoCamo will change to the exact same texture and color as the surface your on.
Graphics: 10/10
This is kinda expected since it is on a next-gen console. It looks nice an smooth.
Easter Eggs & Secrets: 10/10
As MGS veterans may know, there are many easter eggs and stuff in the background. This game still has them, although it is a little tougher to find some.
Conclusion
Basically, if you don't play this game, you probably live in a cave & have no idea what is going on outside the rocky walls.