Incredibly good game. Turn based strategy at its finest. It's weird how attached you can get to a squad of randomly generated soldiers. It's arguably worth it at full price, but luckily it goes on sale relatively frequently.

Enemy Within (DLC) is also absolutely worth it. The two together create an incredibly engrossing time sink.

Worth it for $20? Probably.
Worth it for $5 when it inevitably goes on sale? Absolutely.

Good story, good gameplay, pretty graphics, varied environments, and things hidden behind waterfalls.

If you aren't a fan of quick time events just note that this game has quite a few of them, but they calm down a bit after the first few hours.