StarCraft 2 is probably the best strategy game out there.
The story: As it was expected of Blizzard the story is a masterpiece. Your main goal is to retrieve some ancient artifacts in an effort to stop the rampaging Zergs form destroying the sector. Aside from this, each character you will meet and will join your team will have a personal agenda which you will help complete. The characters background and dialogues are the strong points of the story as they perfectly define Raynor as a character while exposing the world through out the mission they will provide.
The game-play(campaign): Not much has changed from the original formula. While some improvements have been added, like the possibility to have any number of units in a group, better AI for your units and computer opponents the game maintains it's original and engaging mechanics. You will still have to build structures, and gather resources, but the pace at which you do this is more alert and will keep you glued to your seat for hours. each mission however has some original settings so that they don't get repetitive, and as surprising as it sounds they do make the game original in terms of missions. There is always something new that changes, while in some situation the map itself contributes to this feeling, like the missions where a wall of fire is closing in on your base, or where lava covers most of the map every four minutes. Between mission you can play a point and click time of mini game where you move around a battle cruiser as Raynor and interact with the characters learning more about each of them.
The game-play(multi-player): If you have played SC1 in multilayer you will find Sc2 to be as engaging and fun as the original was. There are some improvement, especially for Battle.Net and match making which is automatic now. The new units change the pace and some of the strategies form the original version. Some units will be able to walk over cliffs, jump form one area to the other, or move while they are burrowed. Also most of the special abilities have changed and now fell more balanced and easier to use. Micro is not as import now, but they it can make the difference if you master it.
The changes: aside from some units for each race, and some structures which have changed the game has stayed pretty much the same. And this is a good thing. However all the new units make the game better and very well balanced especially for the Protoss and the Terrans. I must admit the the Zerg feel a little underpowered, but maybe it's just me.
The graphics: the game looks great and runs great on even average computers. The cinematic are absolutely awesome, character models are very well done, especially in the point and click portion of the game.
The sound: sound is probably on of the strongest point of the game. It absolutely amazing. Not only the sound effects and the sound track, but the voice acting is great.
Overall the game is a masterpiece and should not be missed by any strategy fan.