You sound very upset about the success of the game, so I doubt any of the following will matter to you, but for everyone else....
None of the builds from SC 1 apply to SC 2. The damage system was overhauled. The three factions were given even more individual character, yet remain balanced, a feat pulled of very rarely.
The campaign is essentially like playing mass effect, except each mission is an RTS instead of a shooter. It is about 20 hours of gameplay, probably more than that if you play on the hardest difficulty.
The map editor blows the socks off of anything that currently exists to date.
The game is also much more enjoyable as a spectator sport and has an outrageously high skill cap, which is why the South Koreans play it as their national sport.