I was very impressed with this game.  The story, while complicated at times, was very good.  There is a ton of character development.  So much so, that you really care about the characters and what happens to them.  That's always a sign of great storytelling.  The mechanics of the game are pretty much the same as previous Metal Gear games (I have played two of them).  As before, it's a little light on hand to hand combat, but pretty good when it comes to using weapons.  The graphics are terrific.  There are plenty of weapons and upgrades to choose from.  Combat is great. The game emphasizes stealth and evasion, but there are a few times where you can cut loose with your weapons.  The finale is particularly impressive.  It's like watching a movie.  The final showdown with Liquid is fantastic.
  There are some minor flaws that can get a little annoying at times. There are too many cut scenes and some are very very long.  I like playing games more than just watching them. Fortunately, you do have the option of skipping them.  There are a couple times where Otacon leaves you high and dry without giving enough hints, like how to beat some of the more difficult bosses.  Beating Vamp is particularly hard if you don't know what to do. I didn't particularly like Snake being old.  I really wasn't very impressed with him.  It seems like anyone with a pulse can take him down, especially hand to hand combat. In the cut scenes he comes off as a skilled fighter though.  He's also not that smart either.  There were several times during the game that Snake could have finished off Liquid, but he didn't for whatever reason.  He also gets lots of help from Raiden, Drebin, Meryl etc.  So, overall, Snake is about as unimpressive a hero as you can get.
This game is a great addition to the Metal Gear family.  I highly recommend it.

  * * *
Update 10/21:

  I recently got my first taste of the multiplayer option.  The multiplayer itself is pretty good.  The thing that isn't good is all the hoops you have to jump through just to play it.  First of all, the publisher Konami, makes you register with them before you can play mutliplayer.  Naturally they expect some personal information from you, which is annoying.  Then you must set up a game ID and a site user id.  They are very strict with the user id's and you must use underscores, periods, numbers, etc. in your user name.  Why?  My bank doesn't require that much security, why do I need it for d@mn game??  Very annoying and just makes the process more difficult.  Since you can't use anything easy to remember, you are forced to write it down so you won't forget.  Heaven help you if you do forget and lose the paper, for you will have to repeat this whole convoluted process.  After you get your game id all set, Metal Gear will force you to install it's latest upgrade software on your PS3. It will take FOREVER.  I have a very fast FIOS line and it took at least an hour.  Ridiculous.  After all that nonsense is done, wonderful Konami let's you create one, and only one, character to use in the game.  This is where you find out that if you want another character, or to use any of their special items, you will have to pay for them.  Unbelievable.  Konami wants all my personal information for the "honor" of playing online, then has the gall to want to charge me for certain items.  So, when playing online, you will be at a total disadvantage against those who have no problem spending a ton of money to play.  No thanks.
I was very impressed with this game. The story, while complicated at times, was very good. There is a ton of character development. So much so, that you really care about the characters and what happens to them. That's always a sign of great storytelling. The mechanics of the game are pretty much the same as previous Metal Gear games (I have played two of them). As before, it's a little light on hand to hand combat, but pretty good when it comes to using weapons. The graphics are terrific. There are plenty of weapons and upgrades to choose from. Combat is great. The game emphasizes stealth and evasion, but there are a few times where you can cut loose with your weapons. The finale is particularly impressive. It's like watching a movie. The final showdown with Liquid is fantastic. There are some minor flaws that can get a little annoying at times. There are too many cut scenes and some are very very long. I like playing games more than just watching them. Fortunately, you do have the option of skipping them. There are a couple times where Otacon leaves you high and dry without giving enough hints, like how to beat some of the more difficult bosses. Beating Vamp is particularly hard if you don't know what to do. I didn't particularly like Snake being old. I really wasn't very impressed with him. It seems like anyone with a pulse can take him down, especially hand to hand combat. In the cut scenes he comes off as a skilled fighter though. He's also not that smart either. There were several times during the game that Snake could have finished off Liquid, but he didn't for whatever reason. He also gets lots of help from Raiden, Drebin, Meryl etc. So, overall, Snake is about as unimpressive a hero as you can get. This game is a great addition to the Metal Gear family. I highly recommend it. * * *
Update 10/21:

  I recently got my first taste of the multiplayer option. The multiplayer itself is pretty good. The thing that isn't good is all the hoops you have to jump through just to play it. First of all, the publisher Konami, makes you register with them before you can play mutliplayer. Naturally they expect some personal information from you, which is annoying. Then you must set up a game ID and a site user id. They are very strict with the user id's and you must use underscores, periods, numbers, etc. in your user name. Why? My bank doesn't require that much security, why do I need it for d@mn game?? Very annoying and just makes the process more difficult. Since you can't use anything easy to remember, you are forced to write it down so you won't forget. Heaven help you if you do forget and lose the paper, for you will have to repeat this whole convoluted process. After you get your game id all set, Metal Gear will force you to install it's latest upgrade software on your PS3. It will take FOREVER. I have a very fast FIOS line and it took at least an hour. Ridiculous. After all that nonsense is done, wonderful Konami let's you create one, and only one, character to use in the game. This is where you find out that if you want another character, or to use any of their special items, you will have to pay for them. Unbelievable. Konami wants all my personal information for the "honor" of playing online, then has the gall to want to charge me for certain items. So, when playing online, you will be at a total disadvantage against those who have no problem spending a ton of money to play. No thanks.