I had it preloaded and started playing at midnight. Only had two hours of awake time in me, though and only started on the tutorial. Here are the highlights and lowlights so far:
Good:
1. The meta game between missions seems much more deep than I thought it would be. It seems like all the components from the original X-COM are still there. Research, engineering, interception mini-game, base building, even the ability to sell off alien tech to raise cash. There are decisions of consequence here. I was afraid that it got dumbed down. You only have one base, but 'coverage' (i.e building many bases in the original) is established with satellites. Only thing that looks like it was really taken out is base defense. Honestly, though, unless you were playing in masochist mode, losing a base in the original X-COM was a game over event.
2. Loadout and customization. This is a big change and all for the better. Solider management was the ultimate in tedium in the original games. You could spend minutes swapping out weapons and ammo at the beginning of a mission in the original, only to have to repeat the exact same thing on the next mission. Now you can customize every soldier down to the detail. You can change their appearance, name, race, and select from one of about 25 different camo pattern. If you want your troops to look like Ultramarines, you're in luck. The process is a bit tedious and people do die, so it sucks to come up with a good name, tweak the face and camo, and then get the guy wasted 30 seconds into the next mission. It would be nice to have saved presets for certain looks. But all in all, huge awesome plus.
3. Combat is tough and people die. Hardcore mode is included. If you want to play a 'no-save' game, you're supported. If you want to play it on furiously difficult level, you're supported. Thanks Firaxis. The feeling of danger you crave from the original X-COM is still there in spades. I read that you can actually make the game even tougher once you beat it the first time.
4. Rich tactics. Deep gameplay. The game is pretty intuitive and the play is complex and cerebral. Just as a simple example, when playing the tutorial, I developed a scope. Thrilled with my handiwork, I had then engineers make a bunch and didn't think about the fact that 'med-kit' was also available to build. Next mission, one of my soldiers bleeds out. This is the type of decision, mistake and consequence cycle that made X-COM so addictive. Actions in the meta game have consequences in the action game and vice-versa. As far as combat, I didn't get far enough to give a fair review, but the mechanics seem very solid so far. It's turn based, so there's turn-based weirdness of course. You should not expect 'real time' reality when playing as turn-based has many unrealistic conceits.
Cons
1. Graphical strangeness. On occasion, I would get strange flickering or the ground grid would appear super-highlighted. It happened enough for me to notice and consider it distracting. Reviews indicate that there are stranger things yet to come with clipping and absent models. It has taken away slightly from the immersion factor.
2. Tutorial is long, expositional and sometimes unclear. If you play it, you get your hand held a lot, but you're never sure when flexibility opens up. There's a lot of cut-scenes and things to read. Yes, it's all set up for the plot but it feels like it drags. There are points in the tutorial where you're supposed to do something but it's not clear what it is. For example, I was supposed to kill an alien with a soldier. That soldier had a rocket launcher and I could see that I could kill two aliens with one shot. But I needed that rocket for later in the tutorial and it wouldn't let me fire. I thought the game had locked up on me because the only valid thing to do was to fire my primary weapon. Why even let me select and aim the rocket in the first place?
That's only 2 hours. I believe I will lose a lot of my time on this, although Borderlands 2 is still calling me I need to invent something that allows me to play while sleeping.