Yeah, the editor is one of my favorite parts. Me and my brother(Guilect) always create scenario's that we both can play. It's so sophisticated, that we actually made an RPG with it. Well, it was hard to do, but it was very close to one. Pretty sophisticated, if you ask me. Creating maps...playing them...it makes me want to load up the game and play it right now! I probably shouldn't though... I already played quite a bit today.
But, yes, the editor is a prime edition to the StarCraft package.