Haters comparing it to the original are missing out, if you never played XCOM and like chess like tactics try the demo.
I am not going to get into the weeds about contents of the game, I will just explain what makes it great.
This game is like a exciting game of chess (which to me does not exist in real life), so if you don't like chess don't fret at the comparison. The chess reference is due to the strategic/tactical aspect of the game and that it is turn based. What adds an excitement element is you are attached so much to your troops that you have leveled up you cannot afford to lose even one, even if you can afford it you don't want to. You level these guys up, you can even name them (real names and nicknames/callsigns). These guys are tailored to get you through missions, and you will likely put your team together and use the same guys over and over because you know how they meld together. Lose one and OUCH. Yes you can "replace" them with a less experienced soldier or God forbid a rookie, so it is not the same.
The missions play out in a perfect tempo to allow you to really formulate a strategy for beating the mission.....if you take the time to do it. Make hasty decisions and watch your guys die. I love how the classes and abilities of my troops compliment each other in so many ways. When you learn how to use your assault troops for example it opens up all kinds of tactical advantages. The cool thing is the abilities are versatile enough for you to learn how to use them best in conjunction with other troops.
There is also base building, research stuff in between missions which I don't care as much for but it adds to the game.
Don't listen to haters, there is a demo, try it! If it is not for you at least you gave it a chance.