Yes, I played the campaign, I played the training. But that doesn't prepare you for online, because the campaign on normal is super easy (apparently, thats the difficulty I played) and the units are so messed with and changed that it isn't applicable to the multiplayer at all. My skill level is: build SCVs, bulid supply depot, built barracks, build supply depot build SCV, etc etc. By the time I reach 50 supply and have about 30 marines, and 10 maruaders, I go to harrass their base and they already have siege/roach/whatever, my army is decimated, and I type in GG. Honestly, that has been my experience with 10 online matches. Not fun, really demoralizing. I don't see the point in putting anymore time into getting my assed kicked.
Edit: Don't get me wrong, I want to love this game. I want to be able to participate in the online, and be part of the community. But in most games I see some sort of progression or reason for me to keep playing. In this online, I just get hammered and hammered. I don't care how many replays I watch, if my basic skill of making basic units can't compete with other peoples basics skill of making units, what's the point?