Well the single player should occupy most people enough to justify the purchase price. It's whether or not you get sucked into the multi that will determine whether it's a mental game, or just a damn good one.
I think if there's enough of us around here that are into it, that should make for a good gaming group. Some people just aren't that good at 1v1, and having a good friends list makes 2v2, 3v3 melee VERY fun.
In SC1 that's how I got most of my enjoyment.
On another point, I just bought a SteelSeries Xai, as my trusty (and much beloved) MX518 is finally starting to show signs of its age. Has anyone played RTSs with it, what do they think? Worst case, if I don't get on with it, I'll buy another 518.