Very hard to pick a conclusion. Certainly more story driven than original. Has some glitches.
Like I said it is more story driven then original, got a bit of clips on key events. It seems like a sum up of the original, straight to the point, the story is linear and it does not have the twists of the original in which you could be in the lead and then... the aliens throw 10 UFO's, 3 terror sites and 3 kind of new aliens...
Misses some features from the original, makes the game-play faster and easier. You have only 1 base, base invasions are removed from this game, countries that leave x-com project can't return to the pool. I don't know why is this because in the original you could get them back.
Has some nice twists that you don't have in the original but I won't say anything to avoid spoilers.
Difficulty is just right on classic or normal, depending on your experience with this kind of games. Easy is a fast track of the game, and makes you feel like an alien slayer. Impossible is what it says it is, simply impossible, there is no way you can win the game. Like someone said, your chance to win a battle are 1 in 10 or so. So you have to redo missions more than anything.
The worst bug I encountered was in iron-man mode, the game stops auto-saving and you lose the game because the file gets corrupt saying the language of the file changed (I use multiple language keyboard layout)
Multilayer is a downside for this game. I only managed to start 1 game of 10, usually the counterpart leaves before the game start or maybe there is an issue with this also, although I can't confirm this.
To sum it up this game has room for improvement and I believe patches are coming for multiplayer and singleplayer. Also I think a DLC is up soon that will probably cost 50-75% of the game value if I know Firaxis well with their 10euros maps for civ5 and 5euros for a new nation inside game content.