MGS2 in its PC version suffers from technical imperfectness, however that doesn't stop it from being mind-blowing game.
Story starts 2 years after first "Metal Gear Solid". Snake and Otacon became freelancers, and now they make a big world turnè, detsroing various versions of Metal Gear REX, that every developed country with overgrown of ambition is building. Game starts when Snake need to infiltrate a tanker named Discovery, on which board new Metal Gear is held. Quickly after Snake appears Russian mercenaries and Ocelot so everything gets messy really fast. What happens later is already well known for you and if you somehow don't know than you don't need to know (it's better for you to be surprised, believe me).
Anyway, what I really want to say about story is that it's really amazing. Yeah, some of you cold, heartless, emotional bricks, will have one big LOL from it. However if there is still a piece of human , under that destroyed by video games and evil of this world shell, you should cry and feel touched to the bottom of the heart (I know it hurts but you should let it from time to time). I would even say it's better than in first MGS, at least for me. Ideas and problems that Kojima presents in this games are far more developed than anti-nuclear message in the previous game. The only minus of it is that Kojima again try to explain it too much, and treat us like retards who can't bring conclusions themselves. Still, that can't destroy brilliance and greatness of the story.
Cut-scene this time are even more often than in first MGS1. I played something like 14 hours and pure gameplay was like 3-4. I don't consider this however as a disadvantage. I prefer to watch MGS than play it. For me those perfectly directed cinematics are the core essence of pleasure that comes from experiencing MGS. "Sons of Liberty" is also the most "cinematic" game (next to Fahrenheit) I saw in few years, and I really like it in such way. I mentioned before that I prefer to watch than to play. That doesn't mean gameplay sucks. Task and fights you have to take on, during game are very well prepared and will require at same rate your reflex and thinking. I will only add that final 2 boss' fights are pure genius and complete mind-blow.
Gameplay itself wasn't change too much. Now you can shoot from first person view mode. Snake is equipped in tranquilizer gun, to put enemy asleep (don't use it if you want to play as a real soldier, not some rookie). You can hang-over barriers to move unseen, or spy with a special microphone. Still need to sneak behind back of retarded enemies (I know that if they would be more intelligent game would be impossible but that don't change a fact that they are blind and deaf like newborn puppies). To help you in that; you can hide in the lockers (also you find there some items or ammo), that is better solution than a card boxes. While sticked to wall, you can take a pick of what is behind it, or even shoot from such position. There are more small differences (few new items but like magazine with pretty ladies, not changing too much in the gameplay) and new weapons (that I even didn't used) which will help you in heat situations.
In "Substance" you also have few additional elements like: special missions for Snake, VR missions and even skateboard section. That should give a few additional hours of gameplay after watching ending credits. If that's not enough you can take higher difficulty levels, take photos and view it in special album or watch cut-scenes in special theater mode.
Graphics are nice and I have to admit that even now game looks quite nice. There are less objects than in MGS3 but characters models, and some of effects (diving, storm) still are pleasing for the eye. Despite technical aspects, the whole atmosphere that design creates is irresistible. When on the tanker Snake walks during a storm, you can feel wet and cold that just beams from the screen. And whole game is filled with that lovely industrial feeling; from main menu, till game over screen. Characters design is more ambiguous case. Snake and rest of the old fellows looks still great (or even more great because they have an eyes now). O the other hand, newcomers are not always so wonderful. Such characters as Raiden or Fortune didn't amuse me so much. They are not bad, however characters from first MGS in their design were far more stylish and amazing.
Despite physical appearance I must gave honor to Kojima for building characters personalities. Raiden, despite fact that is a lovely young man who could break girls' heart in many teenager tv shows, is not a fully fitting character to a "tactics espionage action" game. I had a lot of problem to like that boy at the beginning. But as game's story progress, Kojima (like every talented devil) convinced me to his ideas and I started to like Raiden. Same with Fortune or Solidus, their stories and motivations make those characters more than a bunch o polygons. The only bad thing I can say (and it's only real disadvantage of "Sons of Liberty", despite screwed PC conversion) is Rose and Fatman. Fatman just looks lame, but Rose is real pain in the butt. She's so irritating that I can't believe Raiden could be attracted by her, and didn't used his killing techniques after first dinner (also I pity all guys who have such girlfriends, sucks to be you).
OK, forget about Rose and my complain, because at every other level "Sons of Liberty" wins with first "Metal Gear Solid". Well, almost. Music is another element that make this game so near-heart-attack-from-excitement-experience that will pump up your emotions to the top. Generally it's far more better than in MGS1 (Harry Gregson-Williams really showed his best) and only thing that I can say is not as great as in previous part is final song that is not so emotional and thrilling as "The Best is Yet to Come". But that's just details that can't change fact I'm all wet listening to some of the tracks.
Overall I have to say Kojima again deliver a complete, and almost perfect game. It's question of taste do you prefer "Sons of Liberty" or "Snake Eater", however for me the second part is as good as legendary MGS1. Yeah it is in few places imperfect, but awesomeness of plot and cut-scenes, many jokes and secrets Kojima and his people inserted in this game, and especially - emotions, that talks to the deepest parts of my soul (if I have one, that is), can't let me describe those 14 hours of playing, as anything else that just pure magic sealed on a DVD.
PS. I gave 9.5 only because it's lame PC version. On PS2 it would be 10.