Terran were spoiled even in sc1 with an abundance of scans wherever on the map you needed detection, and I think that needs to be changed. What's the point of the opponent getting stealth at all if its never gonna be a factor. Zerg and Protoss, you can potentially snipe their overlords and observers, but what can you really do against a Terran?
I think there needs to be more of a choice between getting mules or getting scan. Say, a more expensive scan or a separate upgrade required, like launching a sattelite from the ghost academy.
As it is now you're always gonna get an orbital command early game and mid to late game you're always gonna have instant detection wherever you need it.
Basically I thought of this during a series of games yesterday. Whenever I had the option to nuke an opponent, I'd never do it against a Terran, because he'd scan a second later and kill my ghost, the end. I might be able to dodge overlords or observers, and in any case they would have to GET TO THE GHOST in time and not just press a key and scan. Stealth just isn't viable versus Terran. SC2 is better than SC1 in that regard, but I still think they have it a bit too easy.