True to Blizzard Entertainment form, StarCraft II doesn't need a lot of horsepower to deliver attractive visuals. And this is the beta we're talking about--who knows what performance enhancements the developers may make to the game before it releases. In any case, based on this early release, we think it's safe to say that most gamers will find playable performance accessible without worrying about a PC upgrade. It's just not that kind of game.
If there are any surprises, it's the CPU dependence this game demonstrates. While even the lowest-end graphics card we tested (a Radeon HD 5570) could handle attractive medium graphics settings at 2560x1600, there is a definite reliance on processor speed. The good news is that any modern dual-core CPU over 2.0 GHz should be able to run the game acceptably, and more megahertz will only help. Folks with legacy single-core CPUs below 3.0 GHz are going to have to sacrifice a lot of visual fidelity for playable performance, though, regardless of the graphics card they use.
If you're looking for a comprehensive review of the gameplay, I think it's too early for that. Blizzard Entertainment is still tweaking the title with regular patches and there will likely be a lot more patching and changes before the game is released.
All I can say for now is that the units (and therefore strategies) have been dramatically altered compared to the original, but the interface and art direction have been translated as closely as humanly possible from the original StarCraft we all know and love. With no single-player campaign to try at this early stage and no AI intelligence above “very easy,” the game itself isn't ready for review. What I can do is let you know that it's a heck of a lot of fun and it feels exactly like StarCraft should. When you think about it, those are probably the two best things we could have hoped for from StarCraft II.