Outstanding Strategy Game
Speaking as somebody without much nostalgia for the original title, I have grown to love X-Com: Enemy Unknown the more I have played. The game is exceptionally deep. You always have something new to research and create. You always have some crisis to deal with at all times. There is a lack of dead time and the feeling of barely staying on top of all problems is your constant companion.
You have several jobs for your soldiers to pursue and different builds for those specific builds. A squad heavy with Heavies and Snipers ended up being a favorite as it tended to give you tons of options. Your sniper serves as one of the most effective soldiers as your back up. The heavy becomes a major necessity against the tougher enemies. Support is nice, but it seemed limiting. Not saying the support is useless (I didn't much use health recovery items, but I imagine it can be extremely helpful in the tougher difficulties), but for my particular playstyle, it was not a terribly useful group. Explosives and long distance killing were the secrets to my success, but other manners of attack were equally valid.
There is no lack of things to do between missions. It is wise to keep soldiers in your barracks and to bring along one or two rookies on missions to develop them. You have to work to keep your allies calm, as when things go bad, they will end up freaking out and possibly leaving your group --- which limits your funding to pursue projects and launch more satellites and to build more aircraft to defend against alien incursions. The constant need to generate research to improve your weapons and tactics against enemies is a fun diversion in and of itself. The game lends itself well to numerous replays as you have numerous ways to handle most scenarios.
The game seems long but not tedious. The missions have a similar underpinning but they all play out differently. You'll find enemies you like and enemies you grow to hate (the Thin Man with their irritating poison cloud attack after dying were specific irritants to me). You have to take all of your confrontations slowly as the AI is quite adept at flanking you and corralling you into massive kill zones. And while your characters don't have a lot of personality, the difficulty in building up one to be a major ass kicker makes the risk of losing one of the your more senior soldiers a terrifying prospect, making one be very careful the more powerful you become.
The game has no real flaws. Mission variety is pretty good. You have some where you have to save civilians from an alien attack (which is difficult since the aliens only goal is to kill the civilians and they will do so as quickly as alienly possible), you have to recover alien artifacts, and you have to occasionally just battle a massive ship full of aliens. The missions last long enough to be fun but not repetitive which is a difficult balancing act that a lot of titles cannot pull off.
This is a true must-have title, one of the true greats of this generation. You really need to get it.