Well story was fine, very juicy and i liked it, but well i was shocked when single player was over after my terran campaign....
Anyway. SC2 has LOT of things changed you wont notice on first or second sight.
E.G. units can be resized, and i dont mean all hydras, but ONE special hydra. Eg: you can have 10 hydras in 10 sizes.
Every unit now can have armor of 5 digits (up to 99999), a unit has kills now and can scale with them and so on.
There are very much of this smaller changes that lets you customize your own maps really the way you want them. You got soooo much more possibilities to create something than in sc1.
And well what the heck do you think they should change? Replace every unit with another but still following the same story?
anyway i´m quite satisfied that my SC looks better nowadays