Brood War was a beautiful accident, but it's clear Blizzard isn't going to risk that again with so much on the line.
Starcraft 2 is a fine RTS, I played it since the first beta wave in February. It's got the Starcraft fundamentals and the balance is already pretty spot on, much more so than when the original SC came out (for obvious reasons). But it's tame, it's the only way they could guarantee such balance. Instead of making a ridiculous game that accidentally perfected itself, they are making a by-the-book RTS.
Think about it. Who the hell thinks of the ability Dark Swarm and puts it into an RTS? On paper that sounds like the most game breaking mechanic ever -- yet it worked. They didn't have to make a perfect game in 1998, they just wanted to make a really fun one.
In SC2, you instead get a bunch of hard counters. Roaches beat marines, plain and simple. Spells like Storm are no longer life threatening, Ultralisks are no longer scary, there's no Reaver to threaten your entire economy/army at any moment, micromanagement is hardly as significant, I could go on. The beauty of Starcraft was that it was really simple to play, but became insanely deep and intense when people used units creatively. That's why it's the only video game to become such a huge spectator sport.
But that's me coming from a competitive perspective. This game will do really well for itself, and the competitive scene will thrive because it's forcing the community, and more importantly South Korea, to move on. Still, even from a basic game design viewpoint, SC2 is one of the most anticlimactic sequels in gaming history IMO. The new Battle Net can be argued to be a downgrade from what WC3 introduced, new units aren't terribly interesting, and the voice acting has just taken a huge dive down to mediocrity.
I was thinking of getting this for the campaign, or to review it (sans my bitchy competitive viewpoints of course), but saving $60 plus whatever the next games will set me back is too tempting at this point.
Just to clarify though, I don't think anything is inherently wrong with Starcraft 2. I just stand by the fact that it is much more tamed then its predecessor, and IMO the old Starcraft feel suffers because of it. How important that feel is in making this game as successful as Brood War was remains to be seen.