I have partaken in my fair shair of Starcrafting over the past twenty-four hours. From what I've experienced thus far, I'd say it was worth the wait. The campaign is pretty enjoyable, but in my experience does next to nothing to prepare you for versus. Versus play is a beast of an entirely different species.
Me and some buddies jumped on for some co-op versus the AI, and spent a good few hours getting rofflestomped on various difficulty levels while we learned different strategies and learned the different maps. The computer definitely likes to make a coordinated rush early on in the game and we've found that if you can prepare for and survive that, followed by a quick regrouping and bit of an offensive push, it's not that bad. But man, surviving that first rush can be tougher than it sounds.
I found myself playing with a Starcraft 1 attitude, which is a good foundation to start with, but Starcraft 2 brings a bunch of new little tricks that add another dimension to old strategies. I've definitely got a lot to learn, and while I'm nearly certain my win/loss ratio is always going to lean towards the latter, it's a testament to the game that even getting demolished can be a lot of fun.
I also absolutely adore the new Battle.Net. We got a taste of it via World of Warcraft over the past few months, but now finally having another game integrated into the experience really drives home the social aspect. It's great being able to chat with guildies while playing a different game, and I look forward to seeing Diablo 3 added to the mix in like a million years, or whenever that game finally comes out.