This game have great feel. Battles give nice tactical experience, with options, specialization and leveli up your troops, gearing up. Enemies are sometimes scary and can rip the faces of your troops. Casualties are neccesery.
Nice bonus that it already contains Enemy Withing expansion.
But it is really the feeling of the game, small cinematics, voice overs of your crew this sets mood well.
Potencial drawbacks: Storyline is small size. Localizations could repeat. UFO vs Fighter is not compeling. The chance of to hit could be really random. On second walkthough could leave much worse experience, Gear variety is not that wide.