Simply put: everyone who played the original has had their own experience and their own favorite things about the game.
I liked the scope of the missions and the general feeling of being part of an epic global conflict.
The missions they showed on the quick look were always on tiny maps. Those were small, irrelevant skirmishes, not battles.
I loved scouting through a village, checking each and every house for aliens. I loved the gigantic four-story alien vessels, that were very difficult to shoot down and had tons of aliens on board even after it crashed and you started to clear the site.
Firaxis reduced the scope and therefore kind of dumbed it down for me. Why can't people just recreate an old game by updating the graphics and keeping the core intact? Why did Firaxis have to build ridiculously and insultingly dumb missions like "disarm the bomb" with respawning (!!!) aliens that fall from the sky?
Anyways, the quick look confronted my dreams about this game with reality and I guess I have to be thankful for that..