From the perspective of a non RTS guy.
I rarely play RTS games, I never played any of Blizzards previous RTS games, I only played there Diablo series. I have to admit because its Blizzard and because of all the stories I have heard about the original game my interest level was raised a bit and so I went out and purchased SC2.
First thing to take note of.. Battle.net 2.0 is amazing case closed. Its so user friendly and even on launch day I experienced no issues what so ever. I didnt play alot of the multi player, but I did during the beta stages of the game and the match making system might be the best thats ever been done.
I don't have a lot to say about the multi player except that its easy to learn but you are just scratching the surface, learning all the hotkeys and how to use your units the best way will take months of playing.
I spent most of my time on the Single Player campaign thus far and its awesome. Every mission you get is like a new game. Its not the typical go here and kill all these guys and move on to the next map.. Every mission has collectibles to upgrade your vehicles or troops, also every mission has different objectives which not only keeps the game fresh but its incredibly fun. I love it. The story is told amazingly, nothing else needs to be said about that. Like I said I don't usually play RTS games but this game clearly deserves a play through. For 60 dollars there is alot of value to be had not even mentioning the map creator which can do just about anything you want it to.